
<PAGE>
 
                                                                    EXHIBIT 10.8

                           REVOLVING CREDIT AGREEMENT

                                     among

                     BOSTON PROPERTIES LIMITED PARTNERSHIP

                                      and

                        OTHER BORROWERS WHICH MAY BECOME
                           PARTIES TO THIS AGREEMENT

                                      and

             BANKBOSTON, N.A. (formerly known as The First National
                                Bank of Boston)

                                      and

                          OTHER BANKS WHICH MAY BECOME
                           PARTIES TO THIS AGREEMENT

                                      and

                      BANKBOSTON, N.A. (formerly known as
                      The First National Bank of Boston),
                                    AS AGENT

                                      with

                          BANCBOSTON SECURITIES INC.,
                            ACTING AS LOAN ARRANGER

                           Dated as of June __, 1997
<PAGE>
 
                               TABLE OF CONTENTS
<TABLE>
<CAPTION>
 
Section                                                                    Page
- -------                                                                    ---- 
<S>       <C>                                                              <C>
 
(S)   1.  DEFINITIONS AND RULES OF INTERPRETATION                            1
                                                                          
          (S)1.1.   Definitions                                              1
          (S)1.2.   Rules of Interpretation                                 22
                                                                          
(S)   2.  THE REVOLVING CREDIT FACILITY                                     22
                                                                          
          (S)2.1.   Commitment to Lend                                      22
          (S)2.2.   The Revolving Credit Notes                              23
          (S)2.3.   Interest on Revolving Credit Loans; Fees                24
          (S)2.4.   Requests for Revolving Credit Loans                     24
          (S)2.5.   Conversion Options                                      26
          (S)2.6.   Funds for Revolving Credit Loans                        27
          (S)2.7.   Reduction of Commitment                                 28
                                                                          
(S)   3.  LETTERS OF CREDIT                                                 28
                                                                          
          (S)3.1.   Letter of Credit Commitments                            28
          (S)3.2.   Reimbursement Obligation of the Borrower                30
          (S)3.3.   Letter of Credit Payments; Funding of a Loan            30
          (S)3.4.   Obligations Absolute                                    31
          (S)3.5.   Reliance by Issuer                                      32
          (S)3.6.   Letter of Credit Fee                                    32
                                                                          
(S)   4.  REPAYMENT OF THE REVOLVING CREDIT LOANS                           32
                                                                          
          (S)4.1.   Maturity                                                32
          (S)4.2.   Optional Repayments of Revolving Credit Loans           33
          (S)4.3.   Mandatory Repayment of Loans                            33
                                                                          
(S)   5.  CERTAIN GENERAL PROVISIONS                                        33
                                                                          
          (S)5.1.   Funds for Payments                                      33
          (S)5.2.   Computations                                            34
          (S)5.3.   Inability to Determine Eurodollar Rate                  34
          (S)5.4.   Illegality                                              34
          (S)5.5.   Additional Costs, Etc.                                  35
          (S)5.6.   Capital Adequacy                                        36
          (S)5.7.   Certificate                                             36
</TABLE> 

                                      -i-
<PAGE>
 
<TABLE> 

<S>       <C>                                                               <C>

          (S)(S)5.8.   Indemnity                                            37
          (S)(S)5.9.   Interest on Overdue Amounts                          37
 
(S)(S)6.  GUARANTY                                                          37
 
(S)(S)7.  REPRESENTATIONS AND WARRANTIES                                    37
 
          (S)(S)7.1.   Authority; Etc.                                      38
          (S)(S)7.2.   Governmental Approvals                               40
          (S)(S)7.3.   Title to Properties; Leases                          40
          (S)(S)7.4.   Financial Statements                                 40
          (S)(S)7.5.   No Material Changes, Etc.                            41
          (S)(S)7.6    Franchises, Patents, Copyrights, Etc.                41
          (S)(S)7.7.   Litigation                                           42
          (S)(S)7.8.   No Materially Adverse Contracts                      42
          (S)(S)7.9.   Compliance With Other Instruments, Laws, Etc.        42
          (S)(S)7.10.  Tax Status                                           42
          (S)(S)7.11.  No Event of Default                                  43
          (S)(S)7.12.  Investment Company Acts                              43
          (S)(S)7.13.  Absence of UCC Financing Statements, Etc.            43
          (S)(S)7.14.  Absence of Liens                                     43
          (S)(S)7.15   Intentionally Omitted                                43
          (S)(S)7.16.  Employee Benefit Plans; Multiemployer Plans;         
                       Guaranteed Pension Plans                             43
          (S)(S)7.17.  Regulations U and X                                  43
          (S)(S)7.18.  Environmental Compliance                             43
          (S)(S)7.19.  Subsidiaries                                         45
          (S)(S)7.20.  Loan Documents                                       45
          (S)(S)7.21.  REIT Status                                          46
          (S)(S)7.22.  Initial Public Offering Registration Statement       46
 
(S)(S)8.  AFFIRMATIVE COVENANTS OF THE BORROWER AND THE 
          GUARANTOR                                                         47
 
          (S)(S)8.1.    Punctual Payment                                    47
          (S)(S)8.2.    Maintenance of Office                               47
          (S)(S)8.3.    Records and Accounts                                47
          (S)(S)8.4.    Financial Statements, Certificates and Information  47
          (S)(S)8.5.    Notices                                             50
          (S)(S)8.6.    Existence of Borrower; Maintenance of Properties    52
          (S)(S)8.7.    Existence of Guarantor; Maintenance of REIT Status  
                        of Guarantor; Maintenance of Properties             53
          (S)(S)8.8.    Insurance                                           53
          (S)(S)8.9.    Taxes                                               53
          (S)(S)8.10.   Inspection of Properties and Books                  54
</TABLE> 

                                     -ii-
<PAGE>
 
<TABLE> 

<S>       <C>                                                               <C>

          (S)(S)8.11.   Compliance with Laws, Contracts, Licenses, and
                        Permit                                              54 
          (S)(S)8.12.   Use of Proceeds                                     55
          (S)(S)8.13.   Acquisition of Borrowing Base Property              55
          (S)(S)8.14.   Additional Borrowers; Solvency of Borrowers         55
          (S)(S)8.15.   Further Assurances                                  56
          (S)(S)8.16.   Interest Rate Protection                            56
          (S)(S)8.17.   Environmental Indemnification                       56
          (S)(S)8.18.   Response Actions                                    57
          (S)(S)8.19.   Environmental Assessments                           57
          (S)(S)8.20.   Employee Benefit Plans                              58
          (S)(S)8.21.   No Amendments to Certain Documents                  58
          (S)(S)8.22.   Intentionally Omitted                               58
      
(S)(S)9.  CERTAIN NEGATIVE COVENANTS OF THE BORROWER AND
          THE GUARANTORS                                                    59
                              
          (S)(S)9.1.    Restrictions on Indebtedness                        59
          (S)(S)9.2.    Restrictions on Liens, Etc.                         60
          (S)(S)9.3.    Restrictions on Investments                         62
          (S)(S)9.4.    Merger, Consolidation and Disposition of Assets     63
          (S)(S)9.5.    Compliance with Environmental Laws                  64
          (S)(S)9.6.    Distributions                                       64
          (S)(S)9.7     Hotel Properties                                    64
 
(S)(S)10. FINANCIAL COVENANTS; COVENANTS REGARDING
          BORROWING BASE PROPERTIES                                         65
 
          (S)(S)10.1.   Consolidated Total Indebtedness                     65
          (S)(S)10.2.   Secured Consolidated Total Indebtedness             65
          (S)(S)10.3.   Debt Service Coverage                               65
          (S)(S)10.4.   Unsecured Consolidated Total Indebtedness           65
          (S)(S)10.5.   Net Worth                                           65
          (S)(S)10.6.   Borrowing Base Properties                           65
          (S)(S)10.7.   Borrowing Base Debt Service Coverage                66
 
(S)(S)11. ESCROW CLOSING                                                    66
 
(S)(S)12  CONDITIONS TO THE FIRST ADVANCE                                   67
 
          (S)(S)12.1.   Satisfaction of Escrow Conditions                   67
          (S)(S)12.2.   Loan Documents                                      67
          (S)(S)12.3.   Certified Copies of Organization Documents          67
          (S)(S)12.4.   By-laws; Resolutions                                67
          (S)(S)12.5.   Incumbency Certificate; Authorized Signers          68
          (S)(S)12.6.   Title Policies                                      68
</TABLE> 

                                     -iii-
<PAGE>
 
<TABLE> 

<S>       <C>                                                               <C>


          (S)(S)12.7.   Certificates of Insurance                           68
          (S)(S)12.8.   Hazardous Substance Assessments                     68
          (S)(S)12.9.   Opinion of Counsel Concerning Organization
                        and Loan Documents                                  68
          (S)(S)12.10.  Tax and Securities Law Compliance                   69
          (S)(S)12.11.  Guaranty                                            69
          (S)(S)12.12.  Structural Condition Assurances                     69
          (S)(S)12.13.  Financial Analysis of Borrowing Base Properties     69
          (S)(S)12.14.  Inspection of Borrowing Base Properties             69
          (S)(S)12.15.  Certifications from Government Officials;
                        UCC-11 Reports                                      69
          (S)(S)12.16.  Completion of Initial Public Offering;
                        IPO Proceeds                                        69
          (S)(S)12.17.  Proceedings and Documents                           70
          (S)(S)12.18.  Fees                                                70
          (S)(S)12.19.  Closing Certificate; Compliance Certificate         70
          (S)(S)12.20.  Partnership Documents                               70
          (S)(S)12.21.  Release Documents                                   70
 
(S)(S)13. CONDITIONS TO ALL BORROWINGS                                      70
 
          (S)(S)13.1    Representations True; No Event of Default;
                        Compliance Certificate                              70
          (S)(S)13.2    No Legal Impediment                                 71
          (S)(S)13.3    Governmental Regulation                             71
 
(S)(S)14. EVENTS OF DEFAULT; ACCELERATION; ETC.                             71
 
          (S)(S)14.1.   Events of Default and Acceleration                  71
          (S)(S)14.2.   Termination of Commitments                          76
          (S)(S)14.3.   Remedies                                            76
 
(S)(S)15. SETOFF                                                            76
 
(S)(S)16. THE AGENT                                                         77
 
          (S)(S)16.1.   Authorization                                       77
          (S)(S)16.2.   Employees and Agents                                77
          (S)(S)16.3.   No Liability                                        77
          (S)(S)16.4.   No Representations                                  77
          (S)(S)16.5.   Payments                                            78
          (S)(S)16.6.   Holders of Revolving Credit Notes                   79
          (S)(S)16.7.   Indemnity                                           79
          (S)(S)16.8.   Agent as Bank                                       79
          (S)(S)16.9.   Notification of Defaults and Events of Defalt       79
</TABLE> 

                                     -iv-
<PAGE>
 
<TABLE> 

<S>       <C>                                                               <C>

          (S)(S)16.10.  Duties in the Case of Enforcement                   79
          (S)(S)16.11.  Successor Agent                                     80
          (S)(S)16.12.  Notices                                             80
 
(S)(S)17. EXPENSES                                                          80
                                                         
(S)(S)18. INDEMNIFICATION                                                   81
                                                         
(S)(S)19. SURVIVAL OF COVENANTS, ETC.                                       82
                                                         
(S)(S)20. ASSIGNMENT; PARTICIPATIONS; ETC.                                  83
 
          (S)(S)20.1.   Conditions to Assignments by Banks                  83
          (S)(S)20.2.   Certain Representations and Warranties;      
                        Limitations; Covenants                              83
          (S)(S)20.3.   Register                                            84
          (S)(S)20.4.   New Revolving Credit Notes                          84
          (S)(S)20.5.   Participations                                      85
          (S)(S)20.6.   Pledge by Lender                                    85
          (S)(S)20.7.   No Assignment by Borrower                           85
          (S)(S)20.8.   Disclosure                                          85
          (S)(S)20.9.   Syndication                                         86
 
(S)(S)21. NOTICES, ETC.                                                     86
                                                         
(S)(S)22. BPLP AS AGENT FOR THE BORROWERS                                   87
                                                         
(S)(S)23. GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE                87
                                                         
(S)(S)24. HEADINGS                                                          87
                                                         
(S)(S)25. COUNTERPARTS                                                      87
                                                         
(S)(S)26. ENTIRE AGREEMENT, ETC.                                            87
                                                         
(S)(S)27. WAIVER OF JURY TRIAL AND CERTAIN DAMAGE CLAIMS                    88
                                                         
(S)(S)28. CONSENTS, AMENDMENTS, WAIVERS, ETC.                               88
                                                         
(S)(S)29. SEVERABILITY                                                      89
</TABLE>

                                      -v-
<PAGE>
 
<TABLE> 
<CAPTION> 

EXHIBITS
- --------
<S>  <C> 

A    Form of Revolving Credit Note
B    Form of Loan Request
C    Form of Compliance Certificate
D    Form of Escrow Agreement
E    Form of Closing Certificate
F    Form of Assignment and Assumption Agreement
G    Form of Joinder Agreement
</TABLE> 

                                     -vi-
<PAGE>
 
<TABLE> 
<CAPTION> 
                    Schedules to Revolving Credit Agreement
                    ---------------------------------------
<S>              <C> 
Schedule 1       Borrowers
Schedule 2       Banks
Schedule 3       Borrowing Base Properties
Schedule 4       Banks' Commitments
Schedule 7.7     Litigation
Schedule 7.19    Subsidiaries
</TABLE> 

                                     -vii-
<PAGE>
 
                           REVOLVING CREDIT AGREEMENT
                           --------------------------


           This REVOLVING CREDIT AGREEMENT is made as of the __ day of June,
1997, by and among BOSTON PROPERTIES LIMITED PARTNERSHIP, a Delaware limited
partnership ("BPLP") and the Wholly-owned Subsidiaries (defined below) which are
listed on Schedule 1 hereto (as such Schedule 1 may be amended from time to
          ----------
time) (BPLP and any such Wholly-owned Subsidiary being hereinafter referred to
collectively as the "Borrower" unless referred to in their individual
capacities), having their principal place of business at 8 Arlington Street,
Boston, Massachusetts 02116, BANKBOSTON, N.A. (formerly known as The First
National Bank of Boston) ("BankBoston"), a national banking association having
its principal place of business at 100 Federal Street, Boston, Massachusetts
02110, and the other lending institutions listed on Schedule 2 hereto or which
                                                    ----------
may become parties hereto pursuant to (S)20 (individually, a "Bank" and
collectively, the "Banks") and BANKBOSTON, as agent for itself and each other
Bank.

                                    RECITALS
                                    -------- 

           A.  The Borrower is primarily engaged in the business of owning,
purchasing, developing, constructing, renovating and operating office and
industrial buildings and hotels in the United States.

           B.  Boston Properties, Inc., a Delaware corporation (the
"Guarantor"), is the sole general partner of BPLP, holds in excess of __% of the
partnership interests in BPLP as of the date of this Agreement, and is qualified
to elect REIT status for income tax purposes and has agreed to guaranty the
obligations of the Borrower hereunder and under the other Loan Documents (as
defined below).

           C.  The Borrower and the Guarantor have requested, and the Banks have
agreed to establish, an unsecured revolving credit facility for use by the
Borrower pursuant to the terms and conditions hereof.

           NOW, THEREFORE, in consideration of the mutual covenants and
agreements herein contained, the parties hereto agree as follows:

           (S)1.    DEFINITIONS AND RULES OF INTERPRETATION.
                    ---------------------------------------

           (S)1.1.  Definitions. The following terms shall have the meanings
set forth in this (S)1 or elsewhere in the provisions of this Agreement
referred to below:

           Accountants. In each case, independent certified public accountants
           -----------
reasonably acceptable to the Majority Banks. The Banks hereby acknowledge that
the Accountants may include Coopers & Lybrand, L.L.P. and any other so-called
"big-six" accounting firm.


                                      -1-
<PAGE>
 
           Accounts Payable. See definition of "Consolidated Total
           ----------------
Indebtedness".

           Affiliate. With reference to any Person, (i) any director or
           ---------
executive officer of that Person, (ii) any other Person controlling, controlled
by or under direct or indirect common control of that Person, (iii) any other
Person directly or indirectly holding 10% or more of any class of the capital
stock or other equity interests (including options, warrants, convertible
securities and similar rights) of that Person and (iv) any other Person 10% or
more of any class of whose capital stock or other equity interests (including
options, warrants, convertible securities and similar rights) is held directly
or indirectly by that Person.

           Agent. BankBoston, N.A. acting as agent for the Banks, or any
           -----
successor agent, as permitted by (S)16.

           Agent's Head Office. The Agent's head office located at 100 Federal
           -------------------
Street, Boston, Massachusetts 02110, or at such other location as the Agent may
designate from time to time, or the office of any successor Agent permitted
under (S)16 hereof, provided such office (which need not be such successor
                    --------
Agent's head office) is located in Boston, Massachusetts.

           Agreement. This Revolving Credit Agreement, including the Schedules
           ---------                                                 --------- 
and Exhibits hereto, as the same may be from time to time amended and in effect.

           Agreement of Limited Partnership of BPLP. The Amended and Restated
           ---------------------------------------- 
Agreement of Limited Partnership of BPLP, dated June __, 1997 among the
Guarantor and the limited partners named therein, as amended through the date
hereof and as the same may be further amended from time to time as permitted by
(S)8.21.

           Annualized Borrowing Base Properties Capital Expenditures. For any
           --------------------------------------------------------- 
rolling four (4) calendar quarters, determined as of the last day of a calendar
quarter, an amount equal to $.25 multiplied by the total number of square feet
                                 ---------- --
of the Real Estate Assets which are Borrowing Base Properties on the last day of
such calendar quarter.

           Annualized Capital Expenditures. For any rolling four (4) calendar
           -------------------------------   
quarters, determined as of the last day of a calendar quarter, an amount equal
to $.25 multiplied by the total number of square feet of the Real Estate Assets
        ----------
on the last day of such calendar quarter.

           Applicable L/C Percentage. With respect to any Letter of Credit, a
           -------------------------
per annum percentage equal to the Applicable Margin in effect on the date upon
which such Letter of Credit was issued.

           Applicable Margin. For purposes of this Agreement, the Applicable
           -----------------
Margin shall be equal to the percentage determined for each Rate Period in
accordance with the following:

                                      -2-
<PAGE>
 
        (i)   For the period from the Closing Date through the day after the
date on which the Agent has received the financial statements required to be
delivered pursuant to Section 8.4(b) for the quarter ending June 30, 1997, the
Applicable Margin will equal __%.

        (ii)  For any period during which the Consolidated Total Indebtedness on
the last day of a quarter constituted between 46% and 55% of the Consolidated
Total Adjusted Asset Value for such quarter, the Applicable Margin will equal
1.1%.

        (iii) For any period during which the Consolidated Total Indebtedness on
the last day of a quarter constituted between 36% and 45% of the Consolidated
Total Adjusted Asset Value for such quarter, the Applicable Margin will equal
1%.

        (iv)  For any period during which the Consolidated Total Indebtedness on
the last day of a quarter constituted less than 35% of the Consolidated Total
Adjusted Asset Value for such quarter, the Applicable Margin will equal .90%.

For purposes of determining the Applicable Margin, Consolidated Total
Indebtedness and Consolidated Total Adjusted Asset Value will be tested as of
the end of each fiscal quarter of the Borrower, commencing with the fiscal
quarter ending June 30, 1997, based upon the annual or quarterly financial
statement required to be delivered pursuant to Section 8.4(a) or 8.4(b),
respectively, and, for purposes of determining the interest rate for any Rate
Period hereunder, any interest rate change shall be effective on the date after
the date on which such financial statements are required to be delivered to the
Agent (assuming such financial statement are timely delivered). The Borrower
shall notify the Agent in writing of any change in the Applicable Margin when it
submits the financial statements upon which such change in the Applicable Margin
is based.

           Arranger.  BancBoston Securities Inc.
           --------

           Assumed Test Debt Service. For any fiscal quarter, an amount equal to
           -------------------------
the aggregate amount determined to be the payments which would be required
during such quarter to amortize the average amount of Unsecured Consolidated
Total Indebtedness outstanding during such quarter with respect to the Borrowing
Base Properties, using a twenty-five (25) year mortgage style amortization
schedule, and using an annual interest rate equal to the sum of two percent (2%)
plus the imputed seven (7) year United States Treasury notes annual yield as of
- ----
the last day of such fiscal quarter based upon published quotes for Treasury
notes having seven (7) years to maturity.

           Assignment and Assumption.  See (S)20.1.
           -------------------------

           Average Unused Commitment. For any period of time, the daily average
           -------------------------
difference between (i) the Total Commitment in effect for each day during such
period and (ii) the sum of the principal amount of Revolving Credit Loans
outstanding on each day during such period plus the Maximum Drawing Amount for
                                           ----
each such day during such period.


                                      -3-
<PAGE>
 
           Banks. Collectively, BankBoston and the other lending institutions
           -----
listed on Schedule 2 hereto and any other banks which may provide additional
          ----------
commitments and become parties to this Agreement, and any other Person who
becomes an assignee of any rights of a Bank pursuant to (S)20 or a Person who
acquires all or substantially all of the stock or assets of a Bank.

           Base Rate. The higher of (i) the annual rate of interest announced
           ---------
from time to time by Bank of Boston at its head office in Boston, Massachusetts
as its "base rate" and (ii) one half of one percent (1/2%) above the overnight
federal funds effective rate as published by the Board of Governors of the
Federal Reserve System, as in effect from time to time. Any change in the Base
Rate during an Interest Period shall result in a corresponding change on the
same day in the rate of interest accruing from and after such day on the unpaid
balance of principal of the Base Rate Loans, if any, applicable to such Interest
Period, effective on the day of such change in the Base Rate.

           Base Rate Loans. Those Revolving Credit Loans bearing interest
           ---------------
calculated by reference to the Base Rate.

           Borrower.  As defined in the preamble hereto.
           --------

           Borrowing Base. As determined from time to time, the Borrowing Base
           --------------
Properties.

           Borrowing Base Availability. As at any date of determination an
           ---------------------------
amount equal to the Eligible Amount on such date minus the Maximum Drawing
                                                 ----- ---       
Amount on such date.

           Borrowing Base Conditions. See definition of "Borrowing Base
           -------------------------
Property".

           Borrowing Base Debt Service Coverage Ratio. As of any date of
           ------------------------------------------
determination, the ratio of (i) Borrowing Base Net Operating Income as
determined on such date divided by 4, to (ii) the Assumed Test Debt Service
                        ------- --  
applicable to the quarter upon which the Borrowing Base Net Operating income was
based.

           Borrowing Base Net Operating Income. As of any date of determination,
           ----------------------------------- 
the Net Operating Income calculated with respect to the Real Estate Assets which
are Borrowing Base Properties during the quarter upon which such Net Operating
Income is based, provided that such Net Operating Income shall be adjusted on a
                 --------
pro forma basis to account for Real Estate Assets that were acquired by the
- --- -----
Borrower and added to the Borrowing Base during such quarter by projecting the
results generated by any such Real Estate Asset for the portion of the
applicable quarter during which the Borrower owned (or ground-leased) such Real
Estate Asset over the entire applicable quarter.

           Borrowing Base Property. As of any date of determination, an
           -----------------------
Unencumbered Asset owned by the Borrower that: (i) is a Permitted Property, (ii)
is not the subject of a Disqualifying Structural Event, (iii) is not the subject
of a Disqualifying Environmental 


                                      -4-
<PAGE>
 
Event, (iv) is not a Real Estate Asset Under Development, (v) is wholly-owned or
ground-leased by the Borrower, (vi) is not subject to a Non-Material Breach, and
(vii) has been designated by the Borrower in writing to the Agent as a Real
Estate Asset that is a Borrowing Base Property, provided that on such date of
                                                --------
determination, the Unencumbered Assets that are Borrowing Base Properties shall
have been 85% leased in the aggregate as of the date of such determination, and
provided, further, that each request to include an Unencumbered Asset as a
- --------  -------
Borrowing Base Property shall be accompanied by a compliance certificate in the
form of Exhibit C-5 attached hereto (the foregoing clauses (i) through (vii) and
        -----------
the succeeding provisos being herein referred to collectively as the "Borrowing
               --------
Base Conditions"). The Borrowing Base Properties that constitute the Borrowing
Base on the Closing Date are set forth on Schedule 3.
                                          ---------- 
           Borrowing Base Value. As of any date of determination, an amount
           --------------------
equal to (i) the Borrowing Base Net Operating Income from the Borrowing Base
Properties as determined on such date minus (ii) the amount by which the Annual
                                      -----
Borrowing Base Capital Expenditures applicable to the quarter upon which such
Borrowing Base Net Operating Income was based exceeds the amount deducted for
Capital Expenditures in determining such Borrowing Base Net Operating Income,
with the number resulting from such subtraction being divided by the
                                                      ------- --
Capitalization Rate; provided that such Borrowing Base Net Operating Income
                     -------- 
shall be adjusted on a pro forma basis to account for Real Estate Assets that
                       --- -----
were acquired by the Borrower and added to the Borrowing Base during such
quarter by projecting the results generated by any such Real Estate Asset for
the portion of the applicable quarter during which the Borrower owned (or
ground-leased) such Real Estate Asset over the entire applicable quarter.

           BP Group. Collectively, (i) BPLP, (ii) the Guarantor, (iii) the
           --------
respective Subsidiaries of BPLP and the Guarantor and (iv) the Partially-Owned
Real Estate Holding Entities.

           Buildings. Individually and collectively, the buildings, structures
           ---------
and improvements now or hereafter located on the Real Estate Assets.

           Business Day. Any day on which banking institutions in Boston,
           ------------
Massachusetts, are open for the transaction of banking business and, in the case
of Eurodollar Rate Loans, also a day which is a Eurodollar Business Day.

           Capital Expenditures. Any expenditure for any item that would be
           --------------------
treated or defined as a capital expenditure under GAAP or the Code.

           Capitalization Rate.  The Capitalization Rate shall be 9.5%.
           -------------------

           Capitalized Leases. Leases under which the Borrower or any of its
           ------------------
Subsidiaries or any Partially-Owned Entity is the lessee or obligor, the
discounted future rental obligations under which are required to be capitalized
on the balance sheet of the lessee or obligor in accordance with GAAP.


                                      -5-
<PAGE>
 
           CERCLA.  See (S)7.18.
           ------

           Closing Date. The first date on which all of the conditions set forth
           ------------
in (S)12 have been satisfied.

           Code. The Internal Revenue Code of 1986, as amended and in effect
           ----
from time to time.

           Completed Loan Request. A loan request accompanied by all information
           ----------------------
required to be supplied under the applicable provisions of (S)2.4.

           Commitment. With respect to each Bank, the amount set forth from time
           ---------- 
to time on Schedule 4 hereto as the amount of such Bank's Commitment to make
           ----------
Loans to, and to participate in the issuance, extension and renewal of Letters
of Credit for the account of, the Borrower as such Schedule 4 may be amended
                                                   ----------
from time to time in accordance with the terms of this Agreement.

           Commitment Percentage. With respect to each Bank, the percentage set
           ---------------------
forth on Schedule 4 hereto as such Bank's percentage of the Total Commitment, as
         ----------
such Schedule 4 may be amended from time to time in accordance with the terms of
     ----------
this Agreement.

           Consolidated or consolidated. With reference to any term defined
           ----------------------------
herein, shall mean that term as applied to the accounts of the Borrower and its
Subsidiaries, or the Guarantor and its Subsidiaries (as the case may be),
consolidated in accordance with GAAP in accordance with the terms of this
Agreement.

           Consolidated EBITDA. In relation to the Borrower, the Guarantor and
           -------------------
their respective Subsidiaries for any fiscal quarter, an amount equal to,
without double-counting, the net income or loss of the Borrower, the Guarantor
and their respective Subsidiaries determined in accordance with GAAP (before
minority interests and excluding the adjustment for so-called "straight-line
rent accounting") for such quarter, plus the following to the extent deducted in
                                    ----
computing such Consolidated net income for such quarter: (i) Consolidated Total
Interest Expense for such quarter and (ii) real estate depreciation,
amortization and other extraordinary items for such quarter; and minus all gains
                                                                 ----- 
(or plus all losses) attributable to the sale or other disposition of assets or
    ----
debt restructurings in such quarter, in each case adjusted to include only the
funds actually received in cash by the Borrower, the Guarantor and their
respective Subsidiaries from any Partially-Owned Entity.

           Consolidated Fixed Charges. For any fiscal quarter, an amount equal
           --------------------------
to (i) Consolidated Total Interest Expense for such quarter plus (ii) the
                                                            ----
aggregate amount of scheduled principal payments of Indebtedness (excluding
optional prepayments, balloon payments at maturity and any mid-term balloon
payments of principal with respect to Indebtedness otherwise requiring equal
periodic amortization payments of principal and interest over the term of such
Indebtedness (and any balloon payments at maturity with 


                                      -6-
<PAGE>
 
respect to such Indebtedness)) required to be made during such quarter by the
Borrower, the Guarantor and their respective Subsidiaries on a Consolidated
basis plus (iii) the aggregate amount of capitalized interest required in
      ---- 
accordance with GAAP to be paid or accrued during such quarter by the Borrower,
the Guarantor or their respective Subsidiaries plus (iv) Annualized Capital
                                               ----
Expenditures applicable to such quarter divided by 4.
                                        ------- -- 
           Consolidated Total Adjusted Asset Value. As of any date of
           ---------------------------------------
determination, an amount equal to (a) the sum of (i) the Fair Market Value of
Real Estate as of such date, plus (ii) 100% of the value of Unrestricted Cash
                             ----
and Cash Equivalents on such date, plus (iii) 100% of the Development Costs
incurred and paid to date by the Borrower with respect to any Real Estate Assets
which are Real Estate Assets Under Development on such date, provided that, for
                                                             --------
purposes of this clause (iii), the aggregate amount of Development Costs
included in the calculation of Consolidated Total Adjusted Asset Value shall not
exceed an amount equal to 20% of the sum of the Fair Market Value of Real Estate
Assets on such date plus the value of Unrestricted Cash and Cash Equivalents on
                    ----
such date (the "Eligible Real Estate Development Costs"), plus (iv) the
                                                          ----
aggregate amount of principal under any Mortgage that will be due and payable to
the Borrower or its Subsidiaries (to the extent of Borrower's direct or indirect
interest therein).

           Consolidated Net Worth. As at any date of determination, an amount
           ----------------------
equal to the Consolidated net worth of the Borrower and its Subsidiaries, as
determined in accordance with GAAP.

           Consolidated Total Indebtedness. As of any date of determination,
           -------------------------------
Consolidated Total Indebtedness means for the Borrower, the Guarantor and their
respective Subsidiaries, the sum of (without double-counting), (i) all Accounts
Payable on such date, (ii) all Indebtedness outstanding on such date, and (iii)
all Letters of Credit outstanding on such date, in each case whether Recourse,
Without Recourse or contingent, provided, however, that amounts not drawn under
                                --------  -------
the Revolving Credit Loans or any other Indebtedness on such date shall not be
included in calculating Consolidated Total Indebtedness, and provided, further,
                                                             --------  -------
that (without double-counting) (i) all amounts of guarantees, indemnities for
borrowed money, stop-loss agreements and the like provided by the Borrower, the
Guarantor or any of their respective Subsidiaries, in each case in connection
with and guarantying repayment of amounts outstanding under any other
Indebtedness, (ii) all amounts for which a letter of credit has been issued for
the account of the Borrower, the Guarantor or any of their respective
Subsidiaries, (iii) all amounts of bonds posted by the Borrower, the Guarantor
or any of their respective Subsidiaries guaranteeing performance or payment
obligations and (iv) all liabilities of the Borrower, the Guarantor or any of
their respective Subsidiaries as partners, members or the like for liabilities
of partnerships or other entities in which any of them have an equity interest,
which liabilities are for borrowed money or any of the matters listed in clauses
(i), (ii) or (iii) above shall be included in Consolidated Total Indebtedness.
For purposes hereof, the value of Accounts Payable shall be determined in
accordance with GAAP, and the amount of borrowed money shall equal the sum of
(a) the amount of borrowed money as determined in accordance with GAAP plus (b)
                                                                       ----
the amount of those 


                                      -7-
<PAGE>
 
contingent liabilities for borrowed money set forth in subsections (i) through
(iv) above, but shall exclude any adjustment for so-called "straight-line
interest accounting" or the "constant yield to maturity method" required under
GAAP.

           Consolidated Total Interest Expense. For any fiscal quarter, the
           -----------------------------------
aggregate amount of interest required in accordance with GAAP to be paid or
accrued (but excluding interest reserves funded from the proceeds of any
construction loan), without double-counting, by the Borrower, the Guarantor and
their respective Subsidiaries during such quarter on: (i) all Indebtedness of
the Borrower, the Guarantor and their respective Subsidiaries (including the
Loans and including original issue discount and amortization of prepaid
interest, if any) (ii) all amounts available for borrowing, or for drawing under
letters of credit, if any, issued for the account of the Borrower, the Guarantor
or their respective Subsidiaries, but only if such interest was or is required
to be reflected as an item of expense, and (iii) all commitment fees, agency
fees, facility fees, balance deficiency fees and similar fees and expenses in
connection with the borrowing of money.

           Conversion Request. A notice given by the Borrower to the Agent of
           ------------------
its election to convert or continue a Loan in accordance with (S)2.5.

           Default. When used with reference to this Agreement or any other Loan
           -------
Document, an event or condition specified in (S)14.1 that, but for the
requirement that time elapse or notice be given, or both, would constitute an
Event of Default.

           Development Costs. Construction, development and/or acquisition costs
           -----------------
relating to a Real Estate Asset Under Development, provided that for Real Estate
Assets Under Development owned by any Partially-Owned Entity, the Development
Costs of such Real Estate Asset Under Development shall only be the Borrower's
pro-rata share of the Development Costs of such Real Estate Asset Under
Development (based on the greater of (x) the Borrower's percentage equity
interest in such Partially-Owned Entity or (y) the Borrower's obligation to
provide funds to such Partially-Owned Entity).

           Disqualifying Environmental Event. Any Release or threatened Release
           ---------------------------------
of Hazardous Substances, any violation of Environmental Laws or any other
similar environmental event with respect to any Borrowing Base Property that
will, in the Borrower's and the Agent's reasonable opinion cost in excess of
$1,000,000 to remediate or, which, with respect to the Borrowing Base
Properties, will, in the Borrower's and Agent's reasonable opinion cost in
excess of $20,000,000 in the aggregate to remediate, provided that for all such
                                                     -------- 
environmental events that, individually or in the aggregate, in the Borrower's
and the Agent's reasonable judgment will cost in excess of $20,000,000 to
remediate, the Borrower has received an indemnification, in form and substance
satisfactory to Agent, for an amount at least equal to $10,000,000 from a third
party, who, in the reasonable opinion of Agent, is a credit-worthy entity.

           Disqualifying Structural Event. Any structural issue, which, with
           ------------------------------
respect to any Borrowing Base Property other than rehab properties, will, in the
Borrower's and the 

                                      -8-
<PAGE>
 
Agent's reasonable opinion cost in excess of $1,000,000 to fix or, which, with
respect to the Borrowing Base Properties other than rehab properties, will, in
the Borrower's and Agent's reasonable opinion cost in excess of $10,000,000 in
the aggregate to fix, provided that if, in the Borrower's and Agent's reasonable
opinion, such structural issues will cost in excess of $10,000,000 in the
aggregate to fix, the Borrowing Base Value shall be reduced by an amount equal
to the aggregate of all costs in excess of such $10,000,000.

           Distribution.  With respect to:
           ------------

                          (i)   the Borrower, any distribution of cash or other
                    cash equivalent, directly or indirectly, to the partners of
                    the Borrower; or any other distribution on or in respect of
                    any partnership interests of the Borrower; and

                          (ii)  the Guarantor, the declaration or payment of
                    any dividend on or in respect of any shares of any class of
                    capital stock of Guarantor, other than dividends payable
                    solely in shares of common stock by Guarantor; the purchase,
                    redemption, or other retirement of any shares of any class
                    of capital stock of the Guarantor, directly or indirectly
                    through a Subsidiary of the Guarantor or otherwise; the
                    return of capital by the Guarantor to its shareholders as
                    such; or any other distribution on or in respect of any
                    shares of any class of capital stock of the Guarantor.

           Dollars or $. Dollars in lawful currency of the United States of
           ------------
America.

           Drawdown Date. The date on which any Revolving Credit Loan is made or
           -------------
is to be made, and the date on which any Revolving Credit Loan is converted or
continued in accordance with (S)2.5.

           Eligible Amount. As of the date that any Loan is to be made
           ---------------
hereunder, an amount equal to the lesser of (i) the maximum amount that would
permit Unsecured Consolidated Total Indebtedness (after giving effect to such
Loan) to be less than 60% of Borrowing Base Value on such date and (ii) the
maximum amount that would permit the Borrowing Base Debt Service Coverage Ratio
(after giving effect to such Loan) to be no less than 1.4 to 1.0. In no event,
however, shall Eligible Amount be in excess of $300,000,000.

           Eligible Assignee. Any of (a) a commercial bank organized under the
           -----------------
laws of the United States, or any State- thereof or the District of Columbia,
and having total assets in excess of $1,000,000,000; (b) a savings and loan
association or savings bank organized under the laws of the United States, or
any State thereof or the District of Columbia, and having a net worth of at
least $100,000,000, calculated in accordance with GAAP; and (c) a commercial
bank organized under the laws of any other country (including the central bank
of such country) which is a member of the Organization for Economic Cooperation
and Development (the "OECD"), or a political subdivision of any such 


                                      -9-
<PAGE>
 
country, and having total assets in excess of $1,000,000,000, provided that such
                                                              --------
bank is acting through a branch or agency located in the United States of
America.

           Eligible Real Estate Development Costs. See definition of
           --------------------------------------
"Consolidated Total Adjusted Asset Value".

           Employee Benefit Plan. Any employee benefit plan within the meaning
           ---------------------
of (S)3(3) of ERISA maintained or contributed to by 'the Borrower or any
ERISA Affiliate, other than a Multiemployer Plan.

           Environmental Laws.  See (S)7.18(a).
           ------------------

           Environmental Reports.  See (S)7.18
           --------------------- 

           ERISA. The Employee Retirement Income Security Act of 1974, as
           -----
amended and in effect from time to time.

           ERISA Affiliate. Any Person which is treated as a single employer
           ---------------
with the Borrower under (S)414 of the Code.

           ERISA Reportable Event. A reportable event with respect to a
           ----------------------
Guaranteed Pension Plan within the meaning of (S)4043 of ERISA and the
regulations promulgated thereunder as to which the requirement of notice has not
been waived.

           Escrow Agent. The Person designated as the escrow agent in the Escrow
           ------------ 
Agreement.

           Escrow Agreement. The Escrow Agreement, dated as of the Escrow
           ----------------
Closing Date, among BPLP, the Agent, the Escrow Agent and certain other parties,
the form of which is attached hereto as Exhibit D.
                                        --------- 

           Escrow Closing.  See (S)11.
           --------------

           Escrow Closing Date. The date on which the Loan Documents are placed
           -------------------
in escrow pursuant to the terms of the Escrow Agreement, but in any event, no
later than June 16, 1997 unless the parties hereto otherwise agree in writing.

           Eurocurrency Reserve Rate. For any day with respect to a Eurodollar
           -------------------------
Rate Loan, the maximum rate (expressed as a decimal) at which any Bank subject
thereto would be required to maintain reserves under Regulation D of the Board
of Governors of the Federal Reserve System (or any successor or similar
regulations relating to such reserve requirements) against "Eurocurrency
Liabilities" (as that term is used in Regulation D), if such liabilities were
outstanding. The Eurocurrency Reserve Rate shall be adjusted automatically on
and as of the effective date of any change in the Eurocurrency Reserve Rate.


                                     -10-
<PAGE>
 
           Eurodollar Breakage Costs. With respect to any Eurodollar Rate Loan
           -------------------------
to be prepaid prior to the end of the applicable Interest Period or not drawn
after elected, a prepayment "breakage" fee in an amount determined by the Agent
in the following manner:

                       (i)    First, the Agent shall determine the amount
                    by which (a) the total amount of interest which would have
                    otherwise accrued hereunder on each installment of principal
                    prepaid or not so drawn, during the period beginning on the
                    date of such prepayment or failure to draw and ending on the
                    last day of the applicable Eurodollar Rate Loan Interest
                    Period (the "Reemployment Period"), exceeds (b) the total
                    amount of interest which would accrue, during the
                    Reemployment Period, on any readily marketable bond or other
                    obligation of the United States of America designated by the
                    Agent in its sole discretion at or about the time of such
                    payment, such bond or other obligation of the United States
                    of America to be in an amount equal (as nearly as may be) to
                    the amount of principal so paid or not drawn after elected
                    and to have maturity at the end of the Reemployment Period,
                    and the interest to accrue thereon to take account of
                    amortization of any discount from par or accretion of
                    premium above par at which the same is selling at the time
                    of designation. Each such amount is hereinafter referred to
                    as an "Installment Amount".

                       (ii)   Second, each Installment Amount shall be treated
                    as payable on the last day of the Eurodollar Rate Loan
                    Interest Period which would have been applicable had such
                    principal installment not been prepaid or not borrowed.

                       (iii)  Third, the amount to be paid on each such date
                    shall be the present value of the Installment Amount
                    determined by discounting the amount thereof from the date
                    on which such Installment Amount is to be treated as
                    payable, at the same yield to maturity as that payable upon
                    the bond or other obligation of the United States of America
                    designated as aforesaid by the Agent.

           Eurodollar Business Day. Any day on which commercial banks are open
           -----------------------
for international business (including dealings in Dollar deposits) in London or
such other eurodollar interbank market as may be selected by the Agent in its
sole discretion acting in good faith.

           Eurodollar Rate. For any Interest Period with respect to a Eurodollar
           ---------------  
Rate Loan, the rate per annum equal to the quotient (rounded upwards to the
nearest 1/16 of one percent) of (a) the rate at which the Agent is offered
Dollar deposits two Eurodollar Business Days prior to the beginning of such
Interest Period in an interbank eurodollar market where the eurodollar and
foreign currency and exchange operations of the Agent are customarily conducted
for delivery on the first day of such Interest Period for the 


                                     -11-
<PAGE>
 
number of days comprised therein and in an amount comparable to the amount of
the Eurodollar Rate Loan to which such Interest Period applies, divided by (b) a
number equal to 1.00 minus the Eurocurrency Reserve Rate.

           Eurodollar Rate Loan(s). Revolving Credit Loans bearing interest
           -----------------------
calculated by reference to the Eurodollar Rate.

           Event of Default.  See (S)14.1.
           ----------------

           Exception Property.  See (S)10.6.
           ------------------

           Fair Market Value of Real Estate Assets. As of any date of
           ---------------------------------------
determination, an amount equal to (i) (x) Consolidated EBITDA for the most
recent one (1) complete fiscal quarter (after adjustments for any straight-line
rent accounting), minus (y) $.0625 multiplied by the aggregate square footage of
                  -----            ---------- 
all Real Estate Assets at such date; multiplied by (ii) 4; with the product
                                     ----------
being divided by (iii) the Capitalization Rate.

           Financial Statement Date.  March 31, 1977.
           ------------------------

           Formation Transactions.  As defined in the Prospectus.
           ---------------------- 

           Fronting Bank. BankBoston or such other Bank as the Borrower may
           -------------
identify in accordance with Section 3.1.5.

           "funds from operations". As defined in accordance with resolutions
            ---------------------
adopted by the Board of Governors of the National Association of Real Estate
Investment Trusts as in effect on the Closing Date.

           GAAP. Generally accepted accounting principles, consistently applied.
           ----

           Grandfathered Properties. Individually and collectively, Long Wharf
           ------------------------
Marriott, Boston, Massachusetts and Democracy Center, Bethesda, Maryland whose
individual Borrowing Base Values exceed 15% (and may exceed 20%) of the Total
Commitment in effect from time to time, but whose aggregate Borrowing Base
Values cannot exceed 50% of the Total Commitment in effect from time to time.

           Guaranteed Pension Plan. Any employee pension benefit plan within the
           -----------------------
meaning of (S)3(2) of ERISA maintained or contributed to by the Borrower or
any Guarantor, as the case may be, or any ERISA Affiliate of any of them the
benefits of which are guaranteed on termination in full or in part by the PBGC
pursuant to Title IV of ERISA, other than a Multiemployer Plan.

           Guaranty. The Guaranty dated as of the date hereof made by the
           --------
Guarantor in favor of the Agent and the Banks.


                                     -12-
<PAGE>
 
           Guarantor. Boston Properties, Inc., a Delaware corporation and the
           ---------
sole general partner of the Borrower.

           Hazardous Substances. See (S)7.18(b).
           --------------------

           Indebtedness. All of the following obligations without duplication:
           ------------
(a) the Obligations to the extent outstanding from time to time; (b) all debt
and similar monetary obligations for borrowed money, whether direct or indirect;
(c) all other liabilities for borrowed money secured by any Lien existing on
property owned or acquired subject thereto, whether or not the liability secured
thereby shall have been assumed; (d) reimbursement obligations for letters of
credit; and (e) all guarantees, endorsements and other contingent obligations
for borrowed money whether direct or indirect in respect of indebtedness or
obligations of others.

           Initial Closing Date.  See (S)11.
           --------------------

           Initial Public Offering. The initial public offering of the Guarantor
           -----------------------
as described in the Prospectus.

           Interest Payment Date. As to any Base Rate Loan, the last day of any
           ---------------------
calendar month in which such Loan is outstanding. As to any Eurodollar Rate
Loan, the last day of the applicable Interest Period and when such Loan is due,
and if such Interest Period is longer than three months, at intervals of three
months after the first day thereof, but no less than quarterly.

           Interest Period. With respect to each Revolving Credit Loan , but
           ---------------
without duplication of any other Interest Period, (a) initially, the period
commencing on the Drawdown Date of such Loan and ending on the last day of one
of the following periods (as selected by the Borrower in a Completed Loan
Request): (i) for any Base Rate Loan, the last day of the calendar month, and
(ii) for any Eurodollar Rate Loan, 1, 2, 3, 4 or 6 months; and (b) thereafter,
each period commencing at the end of the last day of the immediately preceding
Interest Period applicable to such Revolving Credit Loan and ending on the last
day of the applicable period set forth in (a)(i) and (ii) above (as selected by
the Borrower in a Conversion Request); provided that all of the foregoing
                                       --------
provisions relating to Interest Periods are subject to the following:

                      (A)   if any Interest Period with respect to a Base
                 Rate Loan would end on a day that is not a Business Day,
                 that Interest Period shall end on the next succeeding
                 Business Day;

                      (B)   if any Interest Period with respect to a Eurodollar
                 Rate Loan would otherwise end on a day that is not a Business
                 Day, that Interest Period shall be extended to the next
                 succeeding Business Day unless the result of such extension
                 would be to carry such Interest Period into another calendar
                 month, in which event such Interest Period shall end on the
                 immediately preceding Business Day;


                                     -13-
<PAGE>
 
                      (C)   if the Borrower shall fail to give notice of
                 conversion as provided in (S)2.5, the Borrower shall be
                 deemed to have requested a conversion of the affected
                 Eurodollar Rate Loan to a Base Rate Loan on the last day of the
                 then current Interest Period with respect thereto;

                      (D)   any Interest Period relating to any Eurodollar Rate
                 Loan that begins on the last Business Day of a calendar month
                 (or on a day for which there is no numerically corresponding
                 day in the calendar month at the end of such Interest Period)
                 shall, subject to subparagraph (E) below, end on the last
                 Business Day of a calendar month; and

                      (E)   any Interest Period that would otherwise extend
                 beyond the Maturity Date shall end on the Maturity Date.

           Investments. All expenditures made and all liabilities incurred
           -----------
(contingently or otherwise, but without double-counting): (i) for the
acquisition of stock, partnership or other equity interests or for the
acquisition of Indebtedness of, or for loans, advances, capital contributions or
transfers of property to, any Person; (ii) in connection with Real Estate Assets
Under Development; and (iii) for the acquisition of any other obligations of any
Person. In determining the aggregate amount of Investments outstanding at any
particular time: (a) there shall be included as an Investment all interest
accrued with respect to Indebtedness constituting an Investment unless and until
such interest is paid; (b) there shall be deducted in respect of each such
Investment any amount received as a return of capital (but only by repurchase,
redemption, retirement, repayment, liquidating dividend or liquidating
distribution); (c) there shall not be deducted in respect of any Investment any
amounts received as earnings on such Investment, whether as dividends, interest
or otherwise, except that accrued interest included as provided in the foregoing
clause (a) may be deducted when paid; and (d) there shall not be deducted from
the aggregate amount of Investments any decrease in the value thereof.

           IPO Proceeds. The proceeds of the Initial Public Offering available
           ------------
to the Borrower (after deducting the costs and expenses incurred in connection
with the Initial Public Offering) in the aggregate amount of not less than (i)
$600,000,000 and (ii) such greater amount as may be necessary to enable the
Borrower to be in compliance with the terms of this Agreement on the Closing
Date.

           Joinder Documents. The one or more Joinder Agreements among the
           -----------------
Agent, the Banks and any Wholly-owned Subsidiary which is to become a Borrower
at any time after the Closing Date, the form of which is attached hereto as
Exhibit G, together with all other documents, instruments and certificates
- ---------
required by any such Joinder Agreement to be delivered by such Wholly-owned
Subsidiary to the Agent and the Banks on the date such Wholly-owned Subsidiary
becomes a Borrower hereunder.


                                     -14-
<PAGE>
 
           Leases. Leases, licenses and agreements, whether written or oral,
           ------
relating to the use or occupation of space in or on the Buildings or on the Real
Estate Assets by Persons other than the Borrower, its Subsidiaries or any
Partially-Owned Entity.

           Leasing Costs. Collectively, leasing commissions, legal fees, design
           -------------
costs, tenant improvement costs and other costs incurred by the Borrower, its
Subsidiaries or any Partially-Owned Entity in connection with entering into
Leases or amendments thereto.

           Letter of Credit.  See (S)3.1.1.
           ----------------

           Letter of Credit Application.  See (S)3.1.1.
           ----------------------------

           Letter of Credit Fee.  See (S)3.6.
           --------------------

           Letter of Credit Participation.  See (S)3.1.4.
           ------------------------------

           Liabilities. All obligations, contingent and otherwise, that in
           -----------
accordance with GAAP should be classified upon the obligor's balance sheet as
liabilities, or to which reference should be made by footnotes thereto,
including in any event and whether or not so classified: (a) all debt and
similar monetary obligations, whether direct or indirect, including, without
limitation, all Indebtedness; (b) all liabilities secured by any mortgage,
pledge, security interest, lien, charge, or other encumbrance existing on
property owned or acquired subject thereto, whether or not the liability secured
thereby shall have been assumed; and (c) all guarantees for borrowed money,
endorsements and other contingent obligations, whether direct or indirect, in
respect of indebtedness or obligations of others, including any obligation to
supply funds (including partnership obligations and capital requirements) to or
in any manner to invest in, directly or indirectly, the debtor, to purchase
indebtedness, or to assure the owner of indebtedness against loss, through an
agreement to purchase goods, supplies, or services for the purpose of enabling
the debtor to make payment of the indebtedness held by such owner or otherwise,
and the obligations to reimburse the issuer in respect of any letters of credit.

           Lien.  See (S)9.2.
           ----  

           Loan Documents. Collectively, this Agreement, the Letter of Credit
           --------------
Applications, the Letters of Credit, the Revolving Credit Notes, the Guaranty,
the Joinder Documents and any and all other agreements, instruments, documents
or certificates now or hereafter evidencing or otherwise relating to the
Revolving Credit Loans and executed and delivered by or on behalf of the
Borrower or its Subsidiaries or the Guarantor or its Subsidiaries in connection
with or in any way relating to the Loans or the transactions contemplated by
this Agreement, and all schedules, exhibits and annexes hereto or thereto, as
any of the same may from time to time be amended and in effect.

           Loans.  The Revolving Credit Loans.
           -----

                                     -15-
<PAGE>
 
           Majority Banks. As of any date, the Banks whose aggregate Commitments
           --------------
constitute at least fifty-one percent (51%) of the Total Commitment.

           Maturity Date. June __, 2000, or such earlier date on which the
           -------------
Revolving Credit Loans shall become due and payable pursuant to the terms
hereof.

           Maximum Drawing Amount. The maximum aggregate amount that the
           ----------------------
beneficiaries may at any time draw under outstanding Letters of Credit, as such
maximum aggregate amount may be reduced from time to time pursuant to the terms
of the Letters of Credit.

           Minimum Commitment. With reference to the Agent, a Commitment equal
           ------------------
to the greater of (i) $25,000,000 or (ii) an amount which is greater than or
equal to the Commitment of any other Bank.

           Moody's.  Moody's Investors Service, Inc., and its successors.
           -------

           Mortgages. Mortgage debt instruments, in which the Borrower holds a
           ---------
direct or indirect interest, for real estate that is developed.

           Multiemployer Plan. Any multiemployer plan within the meaning of
           ------------------
(S)3(37) of ERISA maintained or contributed to b the Borrower or any
Guarantor as the case may be or any ERISA Affiliate.

           Net Operating Income. As at any date of determination, an amount
           --------------------
equal to (i) the aggregate rental and other income from the operation of all
Real Estate Assets during the most recent complete fiscal quarter, multiplied by
4; minus (ii) all expenses and other proper charges incurred in connection with
the operation of such Real Estate Assets (including, without limitation, real
estate taxes, management fees, bad debt expenses and rent under ground leases)
during the most recently completed fiscal quarter multiplied by 4; but, in any
case, before payment of or provision for debt service charges for such fiscal
quarter, income taxes for such fiscal quarter, and depreciation, amortization,
and other non-cash expenses for such fiscal quarter, all as determined in
accordance with GAAP (except that any rent leveling adjustments shall be
excluded from rental income).

           Non-Material Breach.  See (S)14.
           -------------------

           Obligations. All indebtedness, obligations and liabilities of the
           -----------
Borrower and its Subsidiaries to any of the Banks and the Agent, individually or
collectively (but without double-counting), under this Agreement and each of the
other Loan Documents and in respect of any of the Loans and the Revolving Credit
Notes and Reimbursement Obligations incurred and the Letter of Credit
Applications and the Letters of Credit and other instruments at any time
evidencing any thereof, whether existing on the date of this Agreement or
arising or incurred hereafter, direct or indirect, joint or several, absolute or
contingent, matured or unmatured, liquidated or unliquidated, secured or
unsecured, arising by contract, operation of law or otherwise.


                                     -16-
<PAGE>
 
           Organizational Documents. Collectively, (i) the Agreement of Limited
           ------------------------
Partnership of BPLP, (ii) the Certificate of Limited Partnership of BPLP, (iii)
the Certificate of Incorporation of the Guarantor, (iv) the by-laws of the
Guarantor, and (v) all of the partnership agreements, corporate charters and
by-laws, limited liability company operating agreements, joint venture
agreements or similar agreements, charter documents and certificates or other
agreements relating to the formation, organization or governance of any Borrower
(including, without limitation, any Wholly-owned subsidiary who becomes a
Borrower from time to time hereunder), in each case as any of the foregoing may
be amended in accordance with Section 8.21.

           Outside Closing Date.  See (S)11.
           --------------------

           Partially-Owned Entity(ies). Any of the partnerships, associations,
           --------------------------
corporations, limited liability companies, trusts, joint ventures or other
business entities in which the Borrower and/or the Guarantor, directly, or
indirectly through its full or partial ownership of another entity, own an
equity interest, but which is not required in accordance with GAAP to be
consolidated with the Borrower or the Guarantor for financial reporting
purposes.

           PBGC. The Pension Benefit Guaranty Corporation created by (S)4002
           ----
of ERISA and any successor entity or entities having similar responsibilities.

           Permits. All governmental permits, licenses, and approvals necessary
           -------
for the lawful operation and maintenance of the Real Estate Assets.

           Permitted Liens.  Liens permitted by (S)9.2.
           ---------------

           Permitted Property. A property which is an office property, an
           ------------------
industrial property or a hotel property (including any of such properties being
rehabilitated or expanded), including properties having uses ancillary to any of
the foregoing, including, without limitation, retail and parking facilities
which are ancillary to any such office, industrial or hotel property.

           Person. Any individual, corporation, partnership, trust, limited
           ------
liability company, unincorporated association, business, or other legal entity,
and any government (or any governmental agency or political subdivision
thereof).

           Preliminary Prospectus.  See (S)7.22(a).
           ----------------------

           Prospectus.  See (S)7.22(a).
           ----------

           Prospectus Financials.  See (S)7.4(a)
           ---------------------

                                     -17-
<PAGE>
 
           Protected Interest Rate Agreement. An agreement which evidences the
           ---------------------------------
interest protection arrangements required by (S)8.16 hereof, and all
extensions, renewals, modifications, amendments, substitutions and replacements
thereof

           Rate Period. The period beginning on the day following delivery to
           -----------
the Agent of the annual or quarterly financial statements required to be
delivered pursuant to Sections 8.4(a) or (b) and ending two days after the day
on which the next quarterly (or annual, if applicable) financial statements are
delivered to the Agent.

           RCRA.  See (S)7.18.
           ----

           Real Estate Assets. The fixed and tangible properties consisting of
           ------------------
land, buildings and/or other improvements owned or ground-leased by the
Borrower, by the Guarantor or by any other member of the BP Group at the
relevant time of reference thereto, including, without limitation, the Borrowing
Base Properties at such time of reference, but excluding all leaseholds other
than ground leases having an unexpired term of not less than thirty (30) years
from the date hereof (which ground lease unexpired term will include only
renewal options exercisable solely at the ground lessee's option and, if
exercisable prior to the Maturity Date, so exercised).

           Real Estate Assets Under Development. Any Real Estate Assets for
           ------------------------------------
which the Borrower, Guarantor, any of the Borrower's Subsidiaries or any
Partially-Owned Entity is actively pursuing construction of one or more
Buildings or other improvements and for which construction is proceeding to
completion without undue delay from Permit denial, construction delays or
otherwise, all pursuant to such Person's ordinary course of business, provided
that any such Real Estate Asset (or, if applicable, any Building comprising a
portion of any such Real Estate Asset) will no longer be considered a Real
Estate Asset Under Development when a certificate of occupancy has issued for
such Real Estate Asset (or Building) or such Real Estate Asset (or Building) may
otherwise be lawfully occupied for its intended use. Notwithstanding the
foregoing, tenant improvements (where available) to previously constructed
and/or leased Real Estate Assets shall not be considered Real Estate Assets
Under Development.

           Record. The grid attached to any Revolving Credit Note, or the
           ------
continuation of such grid, or any other similar record, including computer
records, maintained by any Bank with respect to any Loan.

           Recourse. With reference to any obligation or liability, any
           --------
liability or obligation that is not Without Recourse to the obligor thereunder,
directly or indirectly. For purposes hereof, a Person shall not be deemed to be
"indirectly" liable for the liabilities or obligations of an obligor solely by
reason of the fact that such Person has an ownership interest in such obligor,
provided that such Person is not otherwise legally liable, directly or
indirectly, for such obligor's liabilities or obligations (e.g., by reason of a
guaranty or contribution obligation, by operation of law or by reason of such
Person being a general partner of such obligor).


                                     -18-
<PAGE>
 
           Registration Statement.  See (S)7.22(a).
           ----------------------

           Reimbursement Obligation. The Borrower's obligation to reimburse the
           ------------------------
Banks and the Agent on account of any drawing under any Letter of Credit as
provided in (S).3.2. Notwithstanding the foregoing, unless the Borrower shall
notify the Agent of its intent to repay the Reimbursement Obligation on the date
of the related drawing under any Letter of Credit as provided in (S).3.2 and
such Reimbursement Obligation is in fact paid by the Borrower on such date, such
Reimbursement Obligation shall simultaneously with such drawing be converted to
and become a Base Rate Loan as set forth in (S)3.3.

           REIT. A "real estate investment trust", as such term is defined in
           ----
Section 856 of the Code.

           Release.  See (S)7.18(c)(iii).
           -------

           Required Banks. As of any date, the Banks whose aggregate Commitments
           --------------
constitute at least sixty-six and two-thirds percent (66-2/3%) of the Total
Commitment.

           Revolving Credit Loan(s). Each and every revolving credit loan made
           ------------------------
or to be made or deemed made by the Banks to the Borrower pursuant to (S)2 or
(S)3.3.

           Revolving Credit Notes. Collectively, the separate promissory notes
           ----------------------
of the Borrower in favor of each Bank in substantially the form of Exhibit A
hereto, in the aggregate principal amount of $300,000,000, dated as of the date
hereof or as of such later date as any Person becomes a Bank under this
Agreement, and completed with appropriate insertions, as each of such notes may
be amended and/or restated from time to time.

           Revolving Credit Note Record. A Record with respect to the Revolving
           ----------------------------
Credit Notes.

           S&P. Standard & Poor's Ratings Group, a division of McGraw-Hill,
           ---
Inc., and its successors.

           SARA. See (S)7.18.
           ----

           SEC.  See (S)7.22(a).
           ---

           SEC Filings. Collectively, (i) the Registration Statement, (ii) the
           -----------
Prospectus, (iii) the Preliminary Prospectus, (iv) each Form 10-K and Form 8-K
filed by the Guarantor with the SEC from time to time and (v) each of the other
public forms and reports filed by the Guarantor with the SEC from time to time.

           Secured Consolidated Total Indebtedness. As of any date of
           ---------------------------------------
determination, the aggregate principal amount of Consolidated Total Indebtedness
of the Borrower, the Guarantor and their Subsidiaries outstanding at such date
secured by a Lien evidenced by 


                                     -19-
<PAGE>
 
a mortgage, deed of trust or other similar security instrument on properties or
other assets of the Borrower, the Guarantor or their Subsidiaries, without
regard to Recourse.

           Subsidiary. Any corporation, association, partnership, limited
           ----------
liability company, trust, joint venture or other business entity which is
required to be consolidated with the Borrower or the Guarantor in accordance
with GAAP.

           Total Commitment. As of any date, the sum of the then current
           ----------------
Commitments of the Banks, provided that the Total Commitment shall not at any
time exceed $300,000,000.

           Type. As to any Revolving Credit Loan, its nature as a Base Rate Loan
           ----
or a Eurodollar Rate Loan.

           Unanimous Bank Approval. The written consent of each Bank that is a
           -----------------------
party to this Agreement at the time of reference.

           Unencumbered Asset. Any Real Estate Asset that on any date of
           ------------------
determination is not subject to any Liens (excluding (i) any such Lien imposed
by the organizational documents of the owner of such asset relating solely to a
restriction on the timing of any sale or refinancing of such Real Estate Asset
which does not materially and adversely affect the value of such Real Estate
Asset and with respect to which the Agent has been specifically notified, and
(ii) any Permitted Liens).

           Uniform Customs. With respect to any Letter of Credit, the Uniform
           ---------------
Customs and Practice for Documentary Credits (1993 Revision), International
Chamber of Commerce Publication No. 500, or any successor version thereof
adopted by the Agent in the ordinary course of its business as a letter of
credit issuer and in effect at the time of issuance of such Letter of Credit.

           Unsecured Consolidated Total Indebtedness. As of any date of
           -----------------------------------------
determination, the aggregate principal amount of Consolidated Total Indebtedness
of the Borrower, the Guarantor and their Subsidiaries outstanding at such date
(including, without limitation, all the Obligations under this Agreement as of
such date), that is not secured by a Lien evidenced by a mortgage, deed of trust
or other similar security interest.

           Unrestricted Cash and Cash Equivalents. As of any date of
           -------------------------------------- 
determination, the sum of (a) the aggregate amount of unrestricted cash then
actually held by the Borrower or any of its Subsidiaries (excluding without
limitation, until forfeited or otherwise entitled to be retained by the Borrower
or any of its Subsidiaries, tenant security and other restricted deposits) and
(b) the aggregate amount of unrestricted cash equivalents (valued at fair market
value) then held by the Borrower or any of its Subsidiaries. As used in this
definition, (i) "unrestricted" means the specified asset is not subject to any
Liens in favor of any Person and (ii) "cash equivalents" means that such asset
has a liquid, par value in cash and is convertible to cash on demand.
Notwithstanding anything 


                                     -20-
<PAGE>
 
contained herein to the contrary, the term Unrestricted Cash and Cash
Equivalents shall not include the Commitments of the Banks to make Loans under
this Agreement.

           Unused Facility Fee.  See (S)2.3(d).
           -------------------

           Value of Unencumbered Assets. As at any date of determination, the
           ----------------------------
sum of (i) the Borrowing Base Value plus (ii) Unrestricted Cash and Cash
                                    ----
Equivalents on such date.

           Wholly-owned Subsidiary. Any Subsidiary which the Borrower and/or the
           -----------------------
Guarantor shall at all times own directly or indirectly (through a Subsidiary or
Subsidiaries) at least a majority (by number of votes or controlling interests)
of the outstanding voting interests and ninety-nine percent (99%) of the
economic interests. For purposes of this definition, (i) with respect to any
Subsidiary of the Borrower or the Guarantor which is a Massachusetts nominee
trust, references to such Subsidiary shall be deemed to be references to the
beneficiary or beneficiaries of such nominee trust, and (ii) BPLP shall not be
permitted to be released from its Obligations as a Borrower hereunder,
notwithstanding any provision of (S)8.14.

           "Without Recourse" or "without recourse". With reference to any
            ----------------      ----------------
obligation or liability, any obligation or liability for which the obligor
thereunder is not liable or obligated other than as to its interest in a
designated Real Estate Asset or other specifically identified asset only,
subject to such limited exceptions to the non-recourse nature of such obligation
or liability, such as, but not limited to, fraud, misappropriation,
misapplication and environmental indemnities, as are usual and customary in like
transactions involving institutional lenders at the time of the incurrence of
such obligation or liability.

           (S)1.2. Rules of Interpretation.
                   -----------------------
 
                               (i)   A reference to any document or agreement
                   shall include such document or agreement as amended, modified
                   or supplemented from time to time in accordance with its
                   terms or the terms of this Agreement.

                               (ii)  The singular includes the plural and
                   the plural includes the singular.

                               (iii) A reference to any law includes any
                   amendment or modification to such law.

                               (iv)  A reference to any Person includes its
                   permitted successors and permitted assigns.

                               (v)   Accounting terms not otherwise defined
                   herein have the meanings assigned to them by generally
                   accepted accounting principles applied on a consistent basis
                   by the accounting entity to which they refer.

                                      -21-
<PAGE>
 
                               (vi)   The words "include", "includes" and
                   "including" are not limiting.

                               (vii)  All terms not specifically defined herein
                   or by generally accepted accounting principles, which terms
                   are defined in the Uniform Commercial Code as in effect in
                   Massachusetts, have the meanings assigned to them therein.

                               (viii) Reference to a particular "(S)" refers
                   to that section of this Agreement unless otherwise indicated.

                               (ix)   The words "herein", "hereof", "hereunder"
                   and words of like import shall refer to this Agreement as a
                   whole and not to any particular section or subdivision of
                   this Agreement.

           (S)2.   THE REVOLVING CREDIT FACILITY.
                   -----------------------------   

           (S)2.1  Commitment to Lend. Subject to the provisions of (S)2.4
                   ------------------
and the other terms and conditions set forth in this Agreement, each of the
Banks severally agrees to lend to the Borrower, and the Borrower may borrow,
repay, and reborrow from each Bank from time to time between the Closing Date
and the Maturity Date upon notice by the Borrower to the Agent (with copies to
the Agent for each Bank) given in accordance with (S)2.4 hereof, such sums as
are requested by the Borrower up to a maximum aggregate principal amount
outstanding (after giving effect to all amounts requested) at any one time equal
to such Bank's Commitment minus an amount equal to such Bank's Commitment
                          -----
Percentage multiplied by the Maximum Drawing Amount; provided that the sum of
           ----------                                --------
the outstanding amount of the Revolving Credit Loans (after giving effect to all
amounts requested) plus, without double-counting the portion, if any, of any
                   ----
Letter of Credit which is drawn and included in the Revolving Credit Loans, all
outstanding Reimbursement Obligations shall not at any time exceed the lesser of
(i) the Total Commitment and (ii) the Borrowing Base Availability at such time,
and provided, further, that at the time the Borrower requests a Revolving Credit
    --------  -------
Loan and after giving effect to the making thereof: (i) in the case of any
borrowing, all of the conditions in (S)13 (and in the case of any initial
borrowing, also the conditions in (S)12) have been met at the time of such
request, and (ii) there has not occurred and is not continuing (or will not
occur by reason of) any Default or Event of Default; it being acknowledged and
agreed that the Borrower shall be permitted to request and borrow Loans if a 
Non-Material Breach (rather than a Default or Event of Default) exists, provided
                                                                        --------
that in the event that such Non-Material Breach relates to a Real Estate Asset
forming part of the Borrowing Base at such time, such Real Estate Asset shall be
excluded from the calculation of Borrowing Base Availability for all purposes in
the compliance certificate accompanying any Completed Loan Request.

           The Revolving Credit Loans shall be made pro rata in accordance with
                                                    --- ----
each Bank's Commitment Percentage. Each request for a Revolving Credit Loan made
pursuant to (S)2.4 hereof shall constitute a representation and warranty by
the Borrower

                                      -22-
<PAGE>
 
that the conditions set forth in (S)12 have been satisfied (except to
the extent any such condition has been waived and/or deferred in writing by the
Agent and the required number of Banks) as of the Closing Date and that the
conditions set forth in (S)13 have been satisfied (except to the extent any such
condition has been waived and/or deferred in writing by the Agent and the
required number of Banks) on the date of such request and will be satisfied
(except to the extent any such condition has been waived and/or deferred in
writing by the Agent and the required number of Banks) on the proposed Drawdown
Date of the requested Loan or issuance of Letter of Credit, as the case may be,
provided that the making of such representation and warranty by the Borrower
- --------
shall not limit the right of any Bank not to lend if such conditions have not
been met. No Revolving Credit Loan shall be required to be made by any Bank
unless (in connection with the initial Revolving Credit Loan or Letter of
Credit) all of the conditions contained in (S)12 have been satisfied (except to
the extent any such condition has been waived and/or deferred in writing by the
Agent and the required number of Banks) as of the Closing Date and unless all of
the conditions set forth in (S)13 have been met at the time of any request for a
Revolving Credit Loan (except to the extent any such condition has been waived
and/or deferred in writing by the Agent and the required number of Banks).

           (S)2.2. The Revolving Credit Notes. The Revolving Credit Loans
                   --------------------------
shall be evidenced by the Revolving Credit Notes. A Revolving Credit Note shall
be payable to the order of each Bank in an aggregate principal amount equal to
such Bank's Commitment. The Borrower irrevocably authorizes each Bank to make or
cause to be made, at or about the time of the Drawdown Date of any Revolving
Credit Loan or at the time of receipt of any payment of principal on such Bank's
Revolving Credit Notes, an appropriate notation on such Bank's Revolving Credit
Note Record reflecting the making of such Revolving Credit Loan or (as the case
may be) the receipt of such payment. The outstanding amount of the Revolving
Credit Loans set forth on such Bank's Revolving Credit Note Record shall be
prima facie evidence of the principal amount thereof owing and unpaid to such
- ----- -----
Bank, but the failure to record, or any error in so recording, any such amount
on such Bank's Revolving Credit Note Record shall not limit or otherwise affect
the rights and obligations of the Borrower hereunder or under any Revolving
Credit Note to make payments of principal of or interest on any Revolving Credit
Note when due.

           (S)2.3. Interest on Revolving Credit Loans; Fees.
                   ----------------------------------------

                   (a)  Each Base Rate Loan shall bear interest for the
period commencing with the Drawdown Date thereof and ending on the last day of
the Interest Period with respect thereto (unless earlier paid in accordance with
(S)4.2) at a rate equal to the Base Rate.

                   (b)  Each Eurodollar Rate Loan shall bear interest for the
period commencing with the Drawdown Date thereof and ending on the last day of
the Interest Period with respect thereto (unless earlier paid in accordance with
(S)4.2) at a rate equal to the Eurodollar Rate determined for such Interest
Period plus the Applicable Margin.

                                      -23-
<PAGE>
 
                      (c)  The Borrower unconditionally promises to pay interest
on each Revolving Credit Loan in arrears on each Interest Payment Date with
respect thereto.

                      (d)  The Borrower agrees to pay to the Agent, for the
accounts of the Banks in accordance with their respective Commitment
Percentages, an unused facility fee calculated at the rate of (i) one-quarter of
one percent (1/4%) per annum on the Average Unused Commitment during each
calendar quarter or portion thereof during which the Average Unused Commitment
is less than or equal to one-half (1/2) of the Total Commitment then in effect
and (ii) one eighth of one percent (1/8%) per annum on the Average Unused
Commitment during each calendar quarter or portion thereof during which the
Average Unused Commitment is greater than one-half (1/2) of the Total Commitment
then in effect (the "Unused Facility Fee"). The Unused Facility Fee shall be
payable quarterly in arrears on the first Business Day of each calendar quarter
for the immediately preceding calendar quarter commencing on the first such date
following the Closing Date through the Maturity Date, with a final payment on
the Maturity Date.

           (S)2.4. Requests for Revolving Credit Loans.
                   -----------------------------------

           The following provisions shall apply to each request by the Borrower
for a Revolving Credit Loan:

                               (i)  The Borrower shall submit a Completed Loan
                      Request to the Agent, together with a duplicate copy of
                      such Completed Loan Request for each Bank which is then a
                      party to this Agreement at the time such loan request is
                      made. Such Completed Loan Requests shall be delivered in
                      separate envelopes to the Agent and be addressed to the
                      Agent and each Bank, respectively, and each such envelope
                      shall be conspicuously marked with the following legend:
                      "LOAN REQUEST -- TIME SENSITIVE -- MUST RESPOND WITHIN
                      [2/4] DAYS" and with the appropriate period filled in.
                      Except as otherwise provided herein, each Completed Loan
                      Request shall be in a minimum amount of $1,000,000 or an
                      integral multiple of $100,000 in excess thereof. Each
                      Completed Loan Request shall be irrevocable and binding on
                      the Borrower and shall obligate the Borrower to accept the
                      Revolving Credit Loans requested from the Banks on the
                      proposed Drawdown Date, unless such Completed Loan Request
                      is withdrawn (x) in the case of a request for a Eurodollar
                      Rate Loan, at least four (4) Business Days prior to the
                      proposed Drawdown Date for such Loan, and (y) in the case
                      of a request for a Base Rate Loan, at least two (2)
                      Business Days prior to the proposed Drawdown Date for such
                      Loan.

                               (ii)  Each Completed Loan Request shall be
                      delivered by the Borrower to the Agent by 10:00 a.m. on
                      any Business Day, and at least two (2) Business Days prior
                      to the proposed Drawdown Date of any Base Rate Loan, and
                      at least four (4) Business Days prior to the proposed
                      Drawdown Date of any Eurodollar Rate Loan.

                                      -24-
<PAGE>
 
                               (iii)  Each Completed Loan Request shall include
                      a completed writing in the form of Exhibit B hereto
                                                         ---------
                      specifying: (1) the principal amount of the Revolving
                      Credit Loan requested, (2) the proposed Drawdown Date of
                      such Revolving Credit Loan, (3) the Interest Period
                      applicable to such Revolving Credit Loan, and (4) the Type
                      of such Revolving Credit Loan being requested.

                                (iv)  No Bank shall be obligated to fund any
                     Revolving Credit Loan or issue any Letter of Credit unless:

                                      (a)  a Completed Loan Request has been
                               timely received by the Agent as provided in
                               subsection (i) above; and

                                      (b)  both before and after giving effect
                               to the Revolving Credit Loan or Letter of Credit
                               to be made or issued pursuant to the Completed
                               Loan Request, all of the conditions contained in
                               (S)12 shall have been satisfied (to the extent
                               such conditions have not been waived and/or
                               deferred in writing by the Agent and the required
                               number of Banks prior to the initial advance) as
                               of the Closing Date, with respect to the initial
                               advance only, and all of the conditions set forth
                               in (S)13 shall have been met, including,
                               without limitation, the condition under
                               (S)13.1 that there be no Default or Event of
                               Default under this Agreement; and

                                      (c)  the Agent shall have received (with
                               copies to the Agent for each Bank) a certificate
                               in the form of Exhibit C-1 hereto signed by the
                                              -----------
                               chief financial officer, treasurer or controller
                               of the Borrower setting forth computations
                               evidencing compliance with the covenants
                               contained in (S)10 on a pro forma basis after
                                                       ---------
                               giving effect to such requested Revolving Credit
                               Loan (including, without limitation, a
                               certification that, to the best of the Borrower's
                               knowledge, if the Borrowing Base Value and the
                               Borrowing Base Debt Service Coverage Ratio were
                               to be calculated on the Drawdown Date of any Loan
                               for the period through the Drawdown Date rather
                               than through the last day of the most recently
                               completed fiscal quarter, there would be
                               sufficient Borrowing Base Availability for the
                               requested Loan), and certifying that, both before
                               and after giving effect to such requested
                               Revolving Credit Loan or Letter of Credit, no
                               Default or Event of Default exists or will exist
                               under this Agreement or any other Loan Document,
                               and that after taking into account such requested
                               Revolving Credit Loan or Letter of Credit, no
                               Default or Event of Default will exist as of the
                               Drawdown Date.

                                      -25-
<PAGE>
 
                               (v)  The Agent will use best efforts to cause the
                       Completed Loan Request to be delivered to each Bank on
                       the same day or the Business Day following the day a
                       Completed Loan Request is received by the Agent.

              (S)2.5.  Conversion Options.
                       ------------------

                       (a)  The Borrower may elect from time to time to convert
any outstanding Revolving Credit Loan to a Revolving Credit Loan of another
Type, provided that (i) with respect to any such conversion of a Eurodollar Rate
Loan to a Base Rate Loan, such conversion shall take place automatically at the
end of the applicable Interest Period unless the Borrower provides notice to the
Agent of its request to continue such Loan as a Eurodollar Rate Loan as provided
in (S)2.5(b) and (S)2.5(a)(ii); (ii) subject to the further proviso at the
end of this (S)2.5(a) and subject to (S)2.5(b) and 2.5(d), with respect to
any conversion of a Base Rate Loan to a Eurodollar Rate Loan (or a continuation
of a Eurodollar Rate Loan, as provided in (S)2.5(b)), the Borrower shall give
the Agent (with copies to the Agent for each Bank) at least four (4) Eurodollar
Business Days' prior written notice of such election, which such notice must be
received by the Agent by 10:00 a.m. on any Business Day; and (iii) no Loan may
be converted into a Eurodollar Rate Loan when any Default or Event of Default
has occurred and is continuing. All or any part of outstanding Revolving Credit
Loans of any Type may be converted as provided herein, provided that each
                                                       --------
Conversion Request relating to the conversion of a Base Rate Loan to a
Eurodollar Rate Loan shall be for an amount equal to $1,000,000 or an integral
multiple of $100,000 in excess thereof and shall be irrevocable by the Borrower.

                       (b)  Any Revolving Credit Loan of any Type may be
continued as such upon the expiration of the Interest Period with respect
thereto (i) in the case of Base Rate Loans, automatically and (ii) in the case
of Eurodollar Rate Loans by compliance by the Borrower with the notice
provisions contained in (S)2.5(a)(ii); provided that no Eurodollar Rate Loan
                                       --------
may be continued as such when any Default or Event of Default has occurred and
is continuing but shall be automatically converted to a Base Rate Loan on the
last day of the first Interest Period relating thereto ending during the
continuance of any Default or Event of Default. The Borrower shall notify the
Agent promptly when any such automatic conversion contemplated by this
(S)2.5(b) is scheduled to occur.

                       (c)  In the event that the Borrower does not notify the
Agent of its election hereunder with respect to any Revolving Credit Loan, such
Loan shall be automatically converted to a Base Rate Loan at the end of the
applicable Interest Period.

                       (d)  The Borrower may not request or elect a Eurodollar
Rate Loan pursuant to (S)2.4, elect to convert a Base Rate Loan to a
Eurodollar Loan pursuant to (S)2.5(a) or elect to continue a Eurodollar Rate
Loan pursuant to (S)2.5(b) if, after giving effect thereto, there would be
greater than six (6) Eurodollar Rate Loans then outstanding. Any Loan Request
for a Eurodollar Rate Loan that would create greater than six (6) Eurodollar
Rate Loans outstanding shall be deemed to be a Loan Request for 

                                      -26-
<PAGE>
 
a Base Rate Loan. By way of explanation of the foregoing, in the event that the
Borrower wishes to convert or continue two or more Loans into one Eurodollar
Rate Loan on the same day and for identical Interest Periods (or borrow an
additional Loan simultaneously with converting or continuing a Loan for
identical Interest Periods), such Eurodollar Rate Loan shall constitute one
single Eurodollar Rate Loan for purposes of this clause (d).

           (S)2.6.  Funds for Revolving Credit Loans.
                    --------------------------------

                    (a)  Subject to the other provisions of this (S)2, not
later than 11:00 a.m. (Boston time) on the proposed Drawdown Date of any
Revolving Credit Loans, each of the Banks will make available to the Agent, at
its Head Office, in immediately available funds, the amount of such Bank's
Commitment Percentage of the amount of the requested Revolving Credit Loan. Upon
receipt from each Bank of such amount, the Agent will make available to the
Borrower the aggregate amount of such Revolving Credit Loan made available to
the Agent by the Banks. All such funds received by the Agent by 11:00 a.m.
(Boston Time) on any Business Day will be made available to the Borrower not
later than 2:00 p.m. on the same Business Day; funds received after such time
will be made available by not later than 11:00 a.m. on the next Business Day.
The failure or refusal of any Bank to make available to the Agent at the
aforesaid time and place on any Drawdown Date the amount of its Commitment
Percentage of the requested Revolving Credit Loan shall not relieve any other
Bank from its several obligation hereunder to make available to the Agent the
amount of its Commitment Percentage of any requested Revolving Credit Loan but
in no event shall the Agent (in its capacity as Agent) have any obligation to
make any funding or shall any Bank be obligated to fund more than its Commitment
Percentage of the requested Revolving Credit Loan or to increase its Commitment
Percentage on account of such failure or otherwise.

                    (b)  The Agent may, unless notified to the contrary by
any Bank prior to a Drawdown Date, assume that such Bank has made available to
the Agent on such Drawdown Date the amount of such Bank's Commitment Percentage
of the Revolving Credit Loan to be made on such Drawdown Date, and the Agent may
(but it shall not be required to), in reliance upon such assumption, make
available to the Borrower a corresponding amount. If any Bank makes available to
the Agent such amount on a date after such Drawdown Date, such Bank shall pay to
the Agent on demand an amount equal to the product of (i) the average, computed
for the period referred to in clause (iii) below, of the weighted average
interest rate paid by the Agent for federal funds acquired by the Agent during
each day included in such period, multiplied by (ii) the amount of such Bank's
                                  ----------
Commitment Percentage of such Revolving Credit Loan, multiplied by (iii) a
                                                     -------------
fraction, the numerator of which is the number of days that elapsed from and
including such Drawdown Date to the date on which the amount of such Bank's
Commitment Percentage of such Revolving Credit Loan shall become immediately
available to the Agent, and the denominator of which is 365. A statement of the
Agent submitted to such Bank with respect to any amounts owing under this
paragraph shall be prima facie evidence of the amount due and owing to the Agent
                   ----- -----
by such Bank.

                                      -27-
<PAGE>
 
           (S)2.7. Reduction of Commitment. The Borrower shall have the right
                   -----------------------
at any time and from time to time upon five (5) Business Days' prior written
notice to the Agent (with copies to the Agent for each Bank) to reduce by
$500,000 or an integral multiple thereof or terminate entirely the unborrowed
portion of the then Total Commitment, whereupon the Commitments of the Banks
shall be reduced pro rata in accordance with their respective Commitment
Percentages by the amount specified in such notice or, as the case may be,
terminated. Upon the effective date of any such reduction or termination, the
Borrower shall pay to the Agent for the respective accounts of the Banks the
full amount of the Unused Facility Fee then accrued and unpaid on the amount of
the reduction. No reduction or termination of the Commitments may be reinstated.

           (S)3.   LETTERS OF CREDIT.
                   -----------------

           (S)3.1. Letter of Credit Commitments.
                   ----------------------------

                   (S)3.1.1.  Commitment to Issue Letters of Credit.
                              -------------------------------------
Subject to the terms and conditions hereof and the execution and delivery by the
Borrower of a letter of credit application on the Fronting Bank's customary form
as part of a Completed Loan Request (a "Letter of Credit Application"), the
Fronting Bank on behalf of the Banks and in reliance upon the agreement of the
Banks set forth in (S)3.1.4 and upon the representations and warranties of
the Borrower contained herein, agrees, in its individual capacity, to issue,
extend and renew for the account of the Borrower one or more letters of credit
(individually, a "Letter of Credit"), in such form as may be requested from time
to time by the Borrower and reasonably agreed to by the Fronting Bank; provided,
                                                                       --------
however, that, after giving effect to such Completed Loan Request, (a) the
- -------
Maximum Drawing Amount plus all Reimbursement Obligations (to the extent, if
any, not yet deemed a Revolving Credit Loan pursuant to (S)3.3), shall not
exceed $50,000,000 at any one time and (b) the sum of (i) all Reimbursement
Obligations (to the extent, if any, not yet deemed a Revolving Credit Loan
pursuant to (S)3.3) and (ii) the amount of all Loans outstanding shall not
exceed the lesser of (x) the Total Commitment in effect at such time and (y) the
Borrowing Base Availability at such time.

                   (S)3.1.2.  Letter of Credit Applications. Each Letter
                              -----------------------------
of Credit Application shall be completed to the reasonable satisfaction of the
Agent and the Fronting Bank. In the event that any provision of any Letter of
Credit Application shall be inconsistent with any provision of this Agreement
(including provisions applicable to a Completed Loan Request) or shall impose
additional financial or other material obligations (other than technical,
administrative and ministerial obligations, whether relating to the mechanics of
a draw under a Letter of Credit or otherwise), then the provisions of this
Agreement shall, to the extent of any such inconsistency or additional material
obligation, govern.

                   (S)3.1.3.  Terms of Letters of Credit. Each Letter of
                              --------------------------
Credit issued, extended or renewed hereunder shall, among other things, (i)
provide for the payment of sight drafts for honor thereunder when presented in
accordance with the terms thereof and when accompanied by the documents
described therein, and (ii) have an expiry date no 

                                      -28-
<PAGE>
 
later than the date which is fourteen (14) days prior to the Maturity Date. Each
Letter of Credit so issued, extended or renewed shall be subject to the Uniform
Customs.

                      (S)3.1.4.  Obligations of Banks with respect to Letters
                                 --------------------------------------------
of Credit. Each Bank severally agrees that it shall be absolutely liable,
- ---------
without regard to the occurrence of any Default or Event of Default or any other
condition precedent whatsoever, to the extent of such Bank's Commitment
Percentage, to reimburse the Fronting Bank on demand pursuant to (S)3.3 for
the amount of each draft paid by the Fronting Bank under each Letter of Credit
to the extent that such amount is not reimbursed by the Borrower pursuant to
(S)3.2 (such agreement for a Bank being called herein the "Letter of Credit
Participation" of such Bank). Each such payment made by a Bank shall be treated
as a purchase by such Bank of a participation in the Fronting Bank's interest in
such Letter of Credit and each Bank shall share, in accordance with its
respective Commitment Percentage, in any interest which accrues and is payable
by the Borrower pursuant to (S)3.2 or otherwise in connection with such
Letter of Credit.

                      (S)3.1.5.  Fronting Bank. Notwithstanding the
                                 -------------
definition of Fronting Bank, in the event that the Borrower reasonably
determines that it would be beneficial to have a Letter of Credit issued by a
Bank with a higher rating than BankBoston has at any applicable time of
reference (as determined by Moody's or S&P), the Borrower shall have the right
to elect any Bank having a higher rating than BankBoston as the Fronting Bank
for that particular Letter of Credit.

           (S)3.2. Reimbursement Obligation of the Borrower. In order to
                   ----------------------------------------
induce the Fronting Bank to issue, extend and renew each Letter of Credit and
the Banks to participate therein, the Borrower hereby agrees, except as
contemplated in (S)3.3 below, to reimburse or pay to the Fronting Bank, for
the account of the Fronting Bank or (as the case may be) the Banks, with respect
to each Letter of Credit issued, extended or renewed by the Fronting Bank
hereunder,

                   (a)   except as otherwise expressly provided in
(S)3.2(b) and (c) or (S)3.3, promptly upon notification by the Fronting
Bank or the Agent that any draft presented under such Letter of Credit is
honored by the Fronting Bank, or the Fronting Bank otherwise makes a payment
with respect thereto, (i) the amount paid by the Fronting Bank under or with
respect to such Letter of Credit, and (ii) any amounts payable pursuant to
(S)5.5 hereof under, or with respect to, such Letter of Credit,

                   (b)   upon the reduction (but not termination) of the Total
Commitment to an amount less than the then Maximum Drawing Amount (after taking
into account all outstanding Loans and Reimbursement Obligations, if any
(without double counting)), an amount equal to such difference, which amount
shall be held by the Agent in an interest-bearing account (with interest to be
added to such account) as cash collateral for the benefit of the Banks and the
Agent for all Reimbursement Obligations, and

                   (c)   upon the termination of the Total Commitment, or the
acceleration of the Reimbursement Obligations with respect to all Letters of
Credit in accordance with 

                                      -29-
<PAGE>
 
(S)14, an amount equal to the then Maximum Drawing Amount on all Letters of
Credit, which amount shall be held by the Agent in an interest-bearing account
(with interest to be added to such account) as cash collateral for the benefit
of the Banks and the Agent for all Reimbursement Obligations.

           Each such payment shall be made to the Agent for the benefit of the
Banks at the Agent's Head Office in immediately available funds. Interest on any
and all amounts not converted to a Loan pursuant to (S)3.3 and remaining
unpaid by the Borrower under this (S)3.2 at any time from the date such
amounts become due and payable (whether as stated in this (S)3.2, by
acceleration or otherwise) until payment in full (whether before or after
judgment) shall be payable to the Agent for the benefit of the Banks on demand
at the rate specified in (S)5.9 for overdue principal on the Loans.

           (S)3.3. Letter of Credit Payments; Funding of a Loan. If any draft
                   --------------------------------------------
shall be presented or other demand for payment shall be made under any Letter of
Credit, the Fronting Bank will use its best efforts to notify the Borrower and
the Banks, on or before the date the Fronting Bank intends to honor such
drawing, of the date and amount of the draft presented or demand for payment and
of the date and time when it expects to pay such draft or honor such demand for
payment and, except to the extent the amount of such draft becomes a Revolving
Credit Loan as set forth in this (S)3.3, Borrower shall reimburse Agent, as
set forth in (S)3.2 above. Notwithstanding anything contained in (S)3.2
above or this (S)3.3 to the contrary, however, unless Borrower shall have
notified the Agent and Fronting Bank prior to 11:00 a.m. (New York time) on the
Business Day immediately prior to the date of such drawing that Borrower intends
to reimburse Fronting Bank for the amount of such drawing with funds other than
the proceeds of the Loans, Borrower shall be deemed to have timely given a
Completed Loan Request pursuant to (S)2.4 to Agent, requesting a Base Rate
Loan on the date on which such drawing is honored and in an amount equal to the
amount of such drawing. The Borrower may thereafter convert any such Base Rate
Loan to a Loan of another Type in accordance with (S)2.5. Each Bank shall, in
accordance with (S)2.6, make available such Bank's Commitment Percentage of
such Loan to Agent, the proceeds of which shall be applied directly by Agent to
reimburse Fronting Bank for the amount of such draw. In the event that any Bank
fails to make available to Agent the amount of such Bank's Commitment Percentage
of such Loan on the date of the drawing, Agent shall be entitled to recover such
amount on demand from such Bank plus any additional amounts payable under
(S)2.6(b) in the event of a late funding by a Bank. The Fronting Bank is
irrevocably authorized by the Borrower and each of the Banks to honor draws on
each Letter of Credit by the beneficiary thereof in accordance with the terms of
the Letter of Credit. The responsibility of the Agent to the Borrower and the
Banks shall be only to determine that the documents (including each draft)
delivered under each Letter of Credit in connection with such presentment shall
be in conformity in all material respects with such Letter of Credit.

           (S)3.4. Obligations Absolute. The Borrower's obligations under
                   --------------------
this (S)3 shall be absolute and unconditional under any and all circumstances
and irrespective of the occurrence of any Default or Event of Default or any
condition precedent whatsoever or 

                                      -30-
<PAGE>
 
any setoff, counterclaim or defense to payment which the Borrower may have or
have had against the Agent, any Bank or any beneficiary of a Letter of Credit.
The Borrower further agrees with the Agent and the Banks that the Agent and the
Banks shall not be responsible for, and the Borrower's Reimbursement Obligations
under (S)3.2 shall not be affected by, among other things, the validity or
genuineness of documents or of any endorsements thereon (so long as the
documents delivered under each Letter of Credit in connection with such
presentment shall be in the form required by, and in conformity in all material
respects with, such Letter of Credit), even if such documents should in fact
prove to be in any or all respects invalid, fraudulent or forged, or any dispute
between or among the Borrower, the beneficiary of any Letter of Credit or any
financing institution or other party to whom any Letter of Credit may be
transferred, or any claims or defenses whatsoever of the Borrower against the
beneficiary of any Letter of Credit or any such transferee. The Agent and the
Banks shall not be liable for any error, omission, interruption or delay in
transmission, dispatch or delivery of any message or advice, however
transmitted, in connection with any Letter of Credit. The Borrower agrees that
any action taken or omitted by the Agent or any Bank under or in connection with
each Letter of Credit and the related drafts and documents, if done in good
faith and absent gross negligence, shall be binding upon the Borrower and shall
not result in any liability on the part of the Agent or any Bank to the
Borrower.

           (S)3.5. Reliance by Issuer. To the extent not inconsistent with
                   ------------------
(S)3.4, the Agent and any Fronting Bank shall be entitled to rely, and shall
be fully protected in relying upon, any Letter of Credit, draft, writing,
resolution, notice, consent, certificate, affidavit, letter, cablegram,
telegram, telecopy, telex or teletype message, statement, order or other
document believed by it to be genuine and correct and to have been signed, sent
or made by the proper Person or Persons and upon advice and statements of legal
counsel, independent accountants and other experts selected by the Agent. The
Agent and any Fronting Bank shall be fully justified in failing or refusing to
take any action under this (S)3 (other than the issuance of a Letter of
Credit pursuant to a Letter of Credit Application and otherwise in accordance
with the terms of this Agreement) unless it shall first have received such
advice or concurrence of the Majority Banks as it reasonably deems appropriate
or it shall first be indemnified to its reasonable satisfaction by the Banks
against any and all liability and expense which may be incurred by it by reason
of taking or continuing to take any such action. The Agent and any Fronting Bank
shall in all cases be fully protected by the Banks in acting, or in refraining
from acting, under this (S)3 in accordance with a request of the Majority
Banks, and such request and any action taken or failure to act pursuant thereto
shall be binding upon the Banks and all future holders of the Notes or of a
Letter of Credit Participation.

           (S)3.6. Letter of Credit Fee. The Borrower shall pay to the Agent
                   --------------------
a fee (in each case, a "Letter of Credit Fee") in an amount equal to the
Applicable L/C Percentage of the undrawn amount of each outstanding Letter of
Credit, which fee (a) shall be payable quarterly in arrears on the first day of
each calendar quarter for the immediately preceding calendar quarter, with a
final payment on the Maturity Date or any earlier date on which the Commitments
shall terminate (which Letter of Credit Fee shall be pro-rated for any calendar
quarter in which such Letter of Credit is issued, drawn upon or 

                                      -31-
<PAGE>
 
otherwise reduced or terminated) and (b) shall be for the accounts of the Banks
as follows: (i) an amount equal to 0.25% per annum of the Letter of Credit Fee
shall be for the account of the Fronting Bank and (ii) the remainder of the
Letter of Credit Fee shall be for the accounts of the Banks (including the
Fronting Bank) pro rata in accordance with their respective Commitment
               --- ----
Percentages.

           (S)4.   REPAYMENT OF THE REVOLVING CREDIT LOANS.
                   ---------------------------------------

           (S)4.1. Maturity. The Borrower promises to pay on the Maturity
                   --------
Date, and there shall become absolutely due and payable on the Maturity Date,
all unpaid principal of the Revolving Credit Loans outstanding on such date,
together with any and all accrued and unpaid interest thereon, the unpaid
balance of the Unused Facility Fee accrued through such date, and any and all
other unpaid amounts due under this Agreement, the Revolving Credit Notes or any
other of the Loan Documents.

           (S)4.2. Optional Repayments of Revolving Credit Loans. The
                   ---------------------------------------------
Borrower shall have the right, at its election, to prepay the outstanding amount
of the Revolving Credit Loans, in whole or in part, at any time without penalty
or premium; provided that the outstanding amount of any Eurodollar Rate Loans
may not be prepaid unless the Borrower pays the Eurodollar Breakage Costs for
each Eurodollar Rate Loan so prepaid at the time of such prepayment. The
Borrower shall give the Agent (with copies to the Agent for each Bank), no later
than 10:00 a.m., Boston time, at least two (2) Business Days' prior written
notice of any prepayment pursuant to this (S)4.2 of any Base Rate Loans, and
at least four (4) Eurodollar Business Days' notice of any proposed prepayment
pursuant to this (S)4.2 of Eurodollar Rate Loans, specifying the proposed
date of prepayment of Revolving Credit Loans and the principal amount to be
prepaid. Each such partial prepayment of the Loans shall be in an amount equal
to $500,000 or an integral multiple of $100,000 in excess thereof or, if less,
the outstanding balance of the Revolving Credit Loans then being repaid, shall
be accompanied by the payment of all charges, if any, outstanding on all
Revolving Credit Loans so prepaid and of all accrued interest on the principal
prepaid to the date of payment, and shall be applied, in the absence of
instruction by the Borrower, first to the principal of Base Rate Loans and then
to the principal of Eurodollar Rate Loans.

           (S)4.3  Mandatory Repayment of Loans. If at any time the sum of
                   ----------------------------
the outstanding amount of the Loans, plus the Maximum Drawing Amount, plus
without double-counting any Revolving Credit Loans, the outstanding
Reimbursement Obligations, if any, exceeds the lesser of (i) the Total
Commitment at such time, or (ii) the Borrowing Base Availability at such time,
the Borrower shall, within fifteen (15) days after receiving notice of such
excess from the Agent (i) pay to the Agent an amount in cash necessary to
eliminate such excess, or (ii) add one (1) or more Real Estate Assets to the
Borrowing Base which have Borrowing Base Values, in the aggregate, sufficient to
eliminate such excess.

                                      -32-
<PAGE>
 
           (S)5.   CERTAIN GENERAL PROVISIONS.
                   --------------------------

           (S)5.1. Funds for Payments.
                   ------------------

                   (a)  All payments of principal, interest, fees, and any other
amounts due hereunder or under any of the other Loan Documents shall be made to
the Agent, for the respective accounts of the Banks or (as the case may be) the
Agent, at the Agent's Head Office, in each case in Dollars and in immediately
available funds.

                   (b)  All payments by the Borrower hereunder and under any of
the other Loan Documents shall be made without setoff or counterclaim and free
and clear of and without deduction for any taxes, levies, imposts, duties,
charges, fees, deductions, withholdings, compulsory liens, restrictions or
conditions of any nature now or hereafter imposed or levied by any jurisdiction
or any political subdivision thereof or taxing or other authority therein unless
the Borrower is compelled by law to make such deduction or withholding. If any
such obligation is imposed upon the Borrower with respect to any amount payable
by it hereunder or under any of the other Loan Documents (except with respect to
taxes on the income or profits of the Agent or any Bank), the Borrower shall pay
to the Agent, for the account of the Banks or (as the case may be) the Agent, on
the date on which such amount is due and payable hereunder or under such other
Loan Document, such additional amount in Dollars as shall be necessary to enable
the Banks to receive the same net amount which the Banks would have received on
such due date had no such obligation been imposed upon the Borrower. The
Borrower will deliver promptly to the Agent (with copies to the Agent for each
Bank) certificates or other valid vouchers for all taxes or other charges
deducted from or paid with respect to payments made by the Borrower hereunder or
under such other Loan Document.

           (S)5.2. Computations. All computations of interest on the Loans
                   ------------
and of other fees to the extent applicable shall be based on a 360-day year and
paid for the actual number of days elapsed. Except as otherwise provided in the
definition of the term "Interest Period" with respect to Eurodollar Rate Loans,
whenever a payment hereunder or under any of the other Loan Documents becomes
due on a day that is not a Business Day, the due date for such payment shall be
extended to the next succeeding Business Day, and interest shall accrue during
such extension. The outstanding amount of the Loans as reflected on the
Revolving Credit Note Record from time to time shall constitute prima facie
evidence of the principal amount thereof.

           (S)5.3. Inability to Determine Eurodollar Rate. In the event,
                   --------------------------------------
prior to the commencement of any Interest Period relating to any Eurodollar Rate
Loan, the Agent shall reasonably and in good faith determine that adequate and
reasonable methods do not exist for ascertaining the Eurodollar Rate that would
otherwise determine the rate of interest to be applicable to any Eurodollar Rate
Loan during any Interest Period, the Agent shall forthwith give notice of such
determination (which shall be conclusive and binding on the Borrower) to the
Borrower and the Banks. In such event (a) any Loan Request with respect to
Eurodollar Rate Loans shall be automatically withdrawn and shall be deemed a
request for Base Rate Loans, (b) each Eurodollar Rate Loan will 

                                      -33-
<PAGE>
 
automatically, on the last day of the then current Interest Period thereof,
become a Base Rate Loan, and (c) the obligations of the Banks to make Eurodollar
Rate Loans shall be suspended, in each case unless and until the Agent
reasonably and in good faith determines that the circumstances giving rise to
such suspension no longer exist, whereupon the Agent shall so notify the
Borrower and the Banks.

           (S)5.4. Illegality. Notwithstanding any other provisions herein, if
                   ----------
any present or future law, regulation, treaty or directive or in the
interpretation or application thereof shall make it unlawful for any Bank to
make or maintain Eurodollar Rate Loans, such Bank shall forthwith give notice of
such circumstances to the Borrower and thereupon (a) the Commitment of such Bank
to make Eurodollar Rate Loans or convert Base Rate Loans to Eurodollar Rate
Loans shall forthwith be suspended and (b) such Bank's Commitment Percentage of
a Eurodollar Rate Loans then outstanding shall be converted automatically to
Base Rate Loans on the last day of each Interest Period applicable to such
Eurodollar Rate Loans or within such earlier period as may be required by law,
all until such time as it is no longer unlawful for such Bank to make or
maintain Eurodollar Rate Loans. The Borrower hereby agrees promptly to pay the
Agent for the account of such Bank, upon demand, any additional amounts
necessary to compensate such Bank for any costs incurred by such Bank in making
any conversion required by this (S)5.4 prior to the last day of an Interest
Period with respect to a Eurodollar Rate Loan, including any interest or fees
payable by such Bank to lenders of funds obtained by it in order to make or
maintain its Eurodollar Rate Loans hereunder.

           (S)5.5. Additional Costs, Etc. If any present or future applicable
                   ---------------------
law, which expression, as used herein, includes statutes, rules and regulations
thereunder and interpretations thereof by any competent court or by any
governmental or other regulatory body or official charged with the
administration or the interpretation thereof and requests, directives,
instructions and notices at any time or from time to time hereafter made upon or
otherwise issued to any Bank or the Agent by any central bank or other fiscal,
monetary or other authority (whether or not having the force of law, but if not
having the force of law, then generally applied by the Banks or the Agent with
respect to similar loans), shall:

                   (a)  subject any Bank or the Agent to any tax, levy, impost,
duty, charge, fee, deduction or withholding of any nature with respect to this
Agreement, the other Loan Documents, any Letters of Credit, such Bank's
Commitment or the Loans (other than taxes based upon or measured by the income
or profits of such Bank or the Agent), or

                   (b)  materially change the basis of taxation (except for
changes in taxes on income or profits) of payments to any Bank of the principal
of or the interest on any Loans or any other amounts payable to the Agent or any
Bank under this Agreement or the other Loan Documents, or

                   (c)  impose or increase or render applicable (other than to
the extent specifically provided for elsewhere in this Agreement) any special
deposit, reserve, 

                                      -34-
<PAGE>
 
assessment, liquidity, capital adequacy or other similar requirements (whether
or not having the force of law) against assets held by, or deposits in or for
the account of, or loans by, or letters of credit issued by, or commitments of
an office of any Bank, or

                     (d)  impose on any Bank or the Agent any other conditions
or requirements with respect to this Agreement, the other Loan Documents, any
Letters of Credit, the Loans, such Bank's Commitment, or any class of loans,
letters of credit or commitments of which any of the Loans or such Bank's
Commitment forms a part;

and the result of any of the foregoing is

                           (i)   to increase the cost to any Bank of making,
                     funding, issuing, renewing, extending or maintaining any of
                     the Loans or such Bank's Commitment or any Letter of
                     Credit, or

                           (ii)  to reduce the amount of principal, interest,
                     Reimbursement Obligation or other amount payable to such
                     Bank or the Agent hereunder on account of such Bank's
                     Commitment, any Letter of Credit or any of the Loans, or

                           (iii) to require such Bank or the Agent to make any
                     payment or to forego any interest or Reimbursement
                     Obligation or other sum payable hereunder, the amount of
                     which payment or foregone interest or Reimbursement
                     Obligation or other sum is calculated by reference to the
                     gross amount of any sum receivable or deemed received by
                     such Bank or the Agent from the Borrower hereunder,

then, and in each such case, the Borrower will, within thirty (30) days after
notice by the Agent or such Bank (such notice to be given promptly by the Agent
or such Bank upon the making of any such determination), at any time and from
time to time and as often as the occasion therefor may arise, pay to such Bank
or the Agent such additional amounts as such Bank or the Agent shall determine
in good faith to be sufficient to compensate such Bank or the Agent for such
additional cost, reduction, payment or foregone interest or other sum, provided
that such Bank or the Agent is generally imposing similar charges on its other
similarly situated borrowers.

           (S)5.6. Capital Adequacy. If any future law, governmental rule,
                   ----------------
regulation, policy, guideline or directive (whether or not having the force of
law, but if not having the force of law, then generally applied by the Banks
with respect to similar loans) or the interpretation thereof by a court or
governmental authority with appropriate jurisdiction affects the amount of
capital required or expected to be maintained by banks or bank holding companies
and any Bank or the Agent determines that the amount of capital required to be
maintained by it is increased by or based upon the existence of Loans made or
deemed to be made pursuant hereto, then such Bank or the Agent may notify the
Borrower of such fact, and the Borrower shall pay to such Bank or the Agent from
time to time, within thirty (30) days after notice by the Agent or such Bank
(such notice to be 

                                      -35-
<PAGE>
 
given promptly by the Agent or such Bank upon the making of any such
determination), as an additional fee payable hereunder, such amount as such Bank
or the Agent shall determine reasonably and in good faith and certify in a
notice to the Borrower to. be an amount that will adequately compensate such
Bank in light of these circumstances for its increased costs of maintaining such
capital. Each Bank and the Agent shall allocate such cost increases among its
customers in good faith and on an equitable basis, and will not charge the
Borrower unless it is generally imposing a similar charge on its other similarly
situated borrowers.

           (S)5.7. Certificate. A certificate setting forth any additional
                   -----------
amounts payable pursuant to (S)5.5 or 5.6 and a brief explanation of such
amounts which are due, including reasonably detailed information regarding the
method and calculation of such amount, submitted by any Bank or the Agent to the
Borrower, shall be prima facie evidence that such amounts are due and owing.
                   ----- -----

           (S)5.8. Indemnity. In addition to the other provisions of this
                   ---------
Agreement regarding such matters, the Borrower agrees to indemnify the Agent and
each Bank and to hold the Agent and each Bank harmless from and against any
loss, cost or expense (including loss of the spread to which such Bank would
have been entitled through the end of the applicable Interest Period in excess
of the applicable interest rate(s) then in effect) that the Agent or such Bank
may sustain or incur as a consequence of (a) a default by the Borrower in the
payment of any principal amount of or any interest on any Eurodollar Rate Loans
as and when due and payable, including any such loss or expense arising from
interest or fees payable by the Agent or such Bank to lenders of funds obtained
by it in order to maintain its Eurodollar Rate Loans, (b) the failure by the
Borrower to make a borrowing or conversion after the Borrower has given a
Completed Loan Request for a Eurodollar Rate Loan or a Conversion Request for a
Eurodollar Rate Loan, and (c) the making of any payment of a Eurodollar Rate
Loan or the making of any conversion of any such Loan to a Base Rate Loan on a
day that is not the last day of the applicable Interest Period with respect
thereto, including interest or fees payable by the Agent or a Bank to lenders of
funds obtained by it in order to maintain any such Eurodollar Rate Loans;
provided, however, that the Borrower shall not be required to so indemnify any
- --------  -------
Bank pursuant to clause (b) above during and for any period of time when such
Bank has wrongfully failed or refused to fund its proportionate share of a Loan
in accordance with the terms of this Agreement and is a Delinquent Bank.

           (S)5.9. Interest on Overdue Amounts. Overdue principal and (to the
                   ---------------------------
extent permitted by applicable law) interest on the Loans and all other overdue
amounts payable hereunder or under any of the other Loan Documents shall bear
interest payable on demand at a rate per annum equal to three percent (3%) above
the Base Rate until such amount shall be paid in full (after as well as before
judgment). In addition, the Borrower shall pay a late charge equal to three
percent (3%) of any amount of interest charges on the Loans which is not paid
within ten (10) days of the date when due.

           (S)6.   GUARANTY. The Guarantor will guaranty the Obligations
                   --------
pursuant to the Guaranty. The Obligations are full recourse obligations of the
Borrower, and all of 

                                      -36-
<PAGE>
 
the respective assets and properties of the Borrower shall be available for the
payment in full in cash and performance of the Obligations.

           (S)7.   REPRESENTATIONS AND WARRANTIES. The Borrower for itself and
                   ------------------------------
for the Guarantor insofar as any such statements relate to the Guarantor
represents and warrants to the Banks all of the statements contained in this
(S)7.

           (S)7.1. Authority, Etc.
                   --------------

                   (a)      Organization: Good Standing.
                            ---------------------------

                                  (i) The Borrower is a limited partnership,
                            general partnership, nominee trust or limited
                            liability company, as the case may be, duly
                            organized, validly existing and in good standing
                            under the laws of its state of organization, unless
                            the failure to be so does not relate to BPLP or the
                            Guarantor and is a Non-Material Breach; the Borrower
                            has all requisite limited partnership, general
                            partnership, trust, limited liability company or
                            corporate, as the case may be, power to own its
                            respective properties and conduct its respective
                            business as now conducted and as presently
                            contemplated, unless any such failure to have any of
                            the foregoing does not relate to BPLP or the
                            Guarantor and is a Non-Material Breach; and the
                            Borrower is in good standing as a foreign entity and
                            is duly authorized to do business in the
                            jurisdictions where the Borrowing Base Properties
                            owned or ground-leased by it are located and in each
                            other jurisdiction where such qualification is
                            necessary except where a failure to be so qualified
                            in such other jurisdiction would not have a
                            materially adverse effect on any of their respective
                            businesses, assets or financial conditions.

                                  (ii) The Guarantor is a corporation duly
                            organized, validly existing and in good standing
                            under the laws of the State of Delaware; each
                            Subsidiary of the Guarantor is duly organized,
                            validly existing and in good standing as a
                            corporation, nominee trust, limited liability
                            company, limited partnership or general partnership,
                            as the case may be, under the laws of the state of
                            its organization, unless the failure to be so does
                            not relate to BPLP and is a Non-Material Breach; the
                            Guarantor and each of its Subsidiaries has all
                            requisite corporate, trust, limited liability
                            company, limited partnership or general partnership,
                            as the case may be, power to own its respective
                            properties and conduct its respective business as
                            now conducted and as presently contemplated, unless
                            any such failure to have any of the foregoing does
                            not relate to BPLP or the Guarantor and is a Non-
                            Material Breach; and the Guarantor is in good
                            standing as a foreign entity and is duly authorized
                            to do business in the jurisdictions where

                                      -37-
<PAGE>
 
                            such qualification is necessary (including in
                            the Commonwealth of Massachusetts) except where a
                            failure to be so qualified in such other would not
                            have a materially adverse effect on the business,
                            assets or financial condition of the Guarantor.

                     (b)    Capitalization. The outstanding equity of BPLP is
                            --------------
comprised of a general partner interest and limited partner interests, all of
which have been duly issued and are outstanding and fully paid and non-
assessable. All of the issued and outstanding general partner interests of the
BPLP are owned and held of record by the Guarantor. There are no outstanding
securities or agreements exchangeable for or convertible into or carrying any
rights to acquire a general partner interest in BPLP. There are no outstanding
commitments, options, warrants, calls or other agreements (whether written or
oral) binding on BPLP or the Guarantor which require or could require BPLP or
the Guarantor to sell, grant, transfer, assign, mortgage, pledge or otherwise
dispose of any general partner interest in BPLP. Except as set forth in the
Agreement of Limited Partnership of BPLP, no general partner interests of BPLP
are subject to any restrictions on transfer or any partner agreements, voting
agreements, trust deeds, irrevocable proxies; or any other similar agreements or
interests (whether written or oral). For so long as any Borrower which is a
Wholly-owned Subsidiary is a Borrower, BPLP and/or the Guarantor own, directly
or indirectly, at least a majority (by number of votes or controlling interests)
of the outstanding voting interests and at least 99% of the economic interests
in each of the Borrowers other than BPLP.

                     (c)    Due Authorization. The execution, delivery and
                            -----------------
performance of this Agreement and the other Loan Documents to which the Borrower
or the Guarantor is or is to become a party and the transactions contemplated
hereby and thereby (i) are within the authority of the Borrower and the
Guarantor, (ii) have been duly authorized by all necessary proceedings on the
part of the Borrower or the Guarantor and any general partner thereof, (iii) do
not materially conflict with or result in any breach or contravention of any
provision of law, statute, rule or regulation to which the Borrower or the
Guarantor is subject or any judgment, order, writ, injunction, license or permit
applicable to the Borrower or the Guarantor, unless any such conflict, breach or
contravention does not relate to BPLP or the Guarantor and is a Non-Material
Breach, (iv) do not conflict with any provision of the agreement of limited
partnership, any certificate of limited partnership, the charter documents or 
by-laws of the Borrower or the Guarantor or any general partner thereof, and (v)
do not contravene any provisions of, or constitute Default or Event of Default
hereunder or a failure to comply with any term, condition or provision of, any
other agreement, instrument, judgment, order, decree, permit, license or
undertaking binding upon or applicable to the Borrower or the Guarantor or any
of the Borrower's or the Guarantor's properties (except for any such failure to
comply under any such other agreement, instrument, judgment, order, decree,
permit, license, or undertaking as would not materially and adversely affect the
condition (financial or otherwise), properties, business or results of
operations of BPLP, the Guarantor or, taken as a whole, the BP Group) or result
in the creation of any mortgage, pledge, security interest, lien, encumbrance or
charge upon any of the properties or assets of the Borrower, the Guarantor.

                                      -38-
<PAGE>
 
                    (d)     Enforceability. Each of the Loan Documents to which
                             -------------
the Borrower or the Guarantor is a party has been duly executed and delivered
and constitutes the legal, valid and binding obligations of the Borrower and the
Guarantor, as the case may be, subject only to applicable bankruptcy,
insolvency, reorganization, moratorium or other laws relating to or affecting
generally the enforcement of creditors' rights and to the fact that the
availability of the remedy of specific performance or injunctive relief is
subject to the discretion of the court before which any proceeding therefor may
be brought.

           (S)7.2.  Governmental Approvals. The execution, delivery and
                    ----------------------
performance by the Borrower of this Agreement and by the Borrower and the
Guarantor of the other Loan Documents to which the Borrower or the Guarantor is
or is to become a party and the transactions contemplated hereby and thereby do
not require (i) the approval or consent of any governmental agency or authority
other than those already obtained or those which would not have a material
adverse effect on BPLP, the Guarantor or, taken as a whole, the BP Group, or
(ii) filing with any governmental agency or authority, other than filings which
will be made with the SEC when and as required by law or deemed appropriate by
the Guarantor.

           (S)7.3.  Title to Properties; Leases.
                    --------------------------- 

           The Borrower and the Guarantor each has good fee or leasehold title
to all of its respective properties, assets and rights of every name and nature
purported to be owned by it, including, without limitation, that:

                    (a)     As of the Closing Date (with respect to Borrowing
Base Properties designated as such on the Closing Date) or the date of
designation as an Borrowing Base Properties (with respect to Borrowing Base
Properties acquired and/or designated as such after the Closing Date), and in
each case to the best of its knowledge thereafter (but only for so long as such
Real Estate Assets continue to be Borrowing Base Properties), the Borrower or
Guarantor holds good and clear record and marketable fee simple or leasehold
title to (or an undivided condominium interest in) the Borrowing Base
Properties, subject to no Liens, except for Permitted Liens and, in the case of
any ground-leased Borrowing Base Property, the terms of such ground lease, as
the same may then or thereafter be amended from time to time in a manner
consistent with the minimum term for ground leases set forth in the definition
of "Real Estate Assets" in (S)1.1 above.

                    (b)     The Borrower and the Guarantor will, as of the
Closing Date (or with respect to the Newport Office Park located in Quincy,
Massachusetts, will within a reasonable period of time after the Closing Date),
own all of the assets as reflected in the financial statements of the Borrower
and the Guarantor described in (S)7.4, the S-11, the Prospectus and the
Preliminary Prospectus or acquired since the date of such financial statements
(except property and assets sold or otherwise disposed of in the ordinary course
of business since that date).

                                      -39-
<PAGE>
 
           (S)7.4.   Financial Statements. The following financial statements
                     --------------------
have been furnished to each of the Banks:

                     (a)     The unaudited pro forma consolidated balance sheet
                                           --- -----
of the Guarantor and its Subsidiaries as of March 31, 1997, and their related
unaudited consolidated statements of operations for the fiscal year ended
December 31, 1996 and for the three months ended March 31, 1997, prepared as if
the Initial Public Offering and all of the Formation Transactions set forth in
the Prospectus had occurred as of March 31, 1997 in the case of the balance
sheet and as of the beginning of the fiscal year presented and carried forward
through the year or interim period presented in the case of the statements of
operations, contained in pages F-1 through F-16, inclusive, of the Prospectus,
together with the financial statements for the Boston Properties Predecessor
Group (as defined in the Prospectus), combined in accordance with GAAP,
contained in pages F-17 through F-32, inclusive, of the Prospectus
(collectively, the "Prospectus Financials"). Such Prospectus Financials have
been prepared in accordance with GAAP and, assuming such Formation Transactions
had occurred as of March 31, 1997 in the case of the pro forma balance sheet and
                                                     --- -----
as of the beginning of the fiscal year presented and carried forward through the
year or interim period presented in the case of the pro forma statements of
                                                    --- -----
operations, fairly present the financial condition of the Guarantor and its
Subsidiaries (or such Boston Properties Predecessor Group, as the case may be)
as at the close of business on the date thereof and the results of operations
for the fiscal year then ended. There are no contingent liabilities of the
Guarantor or any of its Subsidiaries (or such Boston Properties Predecessor
Group, as the case may be) as of such date involving material amounts, known to
the officers of the Guarantor or any of its Subsidiaries (or such Boston
Properties Predecessor Group, as the case may be) not disclosed in said
Prospectus Financials.

                     (b)     A summary of information relating to the Properties
(as defined in the Prospectus) as of _______________, including true, accurate
and complete information in all material respects as to the average annual base
rents, occupancy rates and lease expiration information.

           (S)7.5    No Material Changes, Etc. Since the Financial Statement
                     ------------------------
Date, there has occurred no materially adverse change in the financial condition
or business of BPLP, the Guarantor or, taken as a whole, the BP Group, other
than changes in the ordinary course of business that have not had any materially
adverse effect either individually or in the aggregate on the business or
financial condition of BPLP, the Guarantor or, taken as a whole, the BP Group.
Between the Financial Statement Date and the Closing Date, there has been no
material adverse change to the Net Operating Income of any Real Estate Asset
that is a Borrowing Base property on the Closing Date.

           (S)7.6.   Franchises, Patents, Copyrights, Etc. Except to the extent
                     ------------------------------------
the failure or breach of such representation or warranty constitutes a Non-
Material Breach, the Borrower, Guarantor and each of their respective
Subsidiaries possesses all franchises, patents, copyrights, trademarks, trade
names, licenses and permits, and rights in respect of the foregoing, adequate
for the conduct of their respective businesses substantially as

                                      -40-
<PAGE>
 
now conducted without known conflict with any rights of others, including all
material Permits.

           (S)7.7 Litigation. Except as stated on Schedule 7.7, there are no
                  ----------                      ------------
actions, suits, proceedings or investigations of any kind pending or, to the
Borrower's knowledge, threatened against the Borrower, the Guarantor or any of
their respective Subsidiaries before any court, tribunal or administrative
agency or board that, if adversely determined, might, either individually or in
the aggregate, materially adversely affect the properties, assets, financial
condition or business of BPLP, the Guarantor or, taken as a whole, the BP Group,
or materially impair the right of BPLP, the Guarantor or, taken as a whole, the
BP Group, to carry on their respective businesses substantially as now conducted
by them, or result in any substantial liability not adequately covered by
insurance, or for which adequate reserves are not maintained, as reflected in
the applicable consolidated financial statements or SEC Filings of the Borrower
and the Guarantor, or which question the validity of this Agreement or any of
the other Loan Documents, or any action taken or to be taken pursuant hereto or
thereto.

           (S)7.8. No Materially Adverse Contracts, Etc. Neither the
                   ------------------------------------
Borrower, the Guarantor nor any of their respective Subsidiaries is subject to
any charter, corporate, partnership or other legal restriction, or any judgment,
decree, order, rule or regulation that has or is reasonably expected in the
future to have (and with respect solely to any restriction on the timing of any
sale or refinancing of a Real Estate Asset which would be an acceptable Lien
under the definition of "Unencumbered Asset" contained in an Organizational
Document, such expectation existed at the time such restriction was imposed) a
materially adverse effect on the respective businesses, assets or financial
conditions of BPLP, the Guarantor or, taken as a whole, the BP Group. None of
the Borrower, the Guarantor or any of their respective Subsidiaries is a party
to any contract or agreement that has or is expected, in the judgment of their
respective officers, to have any materially adverse effect on the respective
businesses of the BPLP, the Guarantor or, taken as a whole, the BP Group.

           (S)7.9. Compliance With Other Instruments, Laws, Etc. Neither the
                      --------------------------------------------
Borrower, the Guarantor nor any of their respective Subsidiaries is in violation
of any provision of its partnership agreement or charter, as the case may be, or
any respective agreement or instrument to which it may be subject or by which it
or any of its properties may be bound or any decree, order, judgment, statute,
license, rule or regulation, in any of the foregoing cases in a manner that
could result, individually or in the aggregate, in the imposition of substantial
penalties or materially and adversely affect the financial condition, properties
or businesses of the BPLP, the Guarantor or, taken as a whole, the BP Group.

           (S)7.10. Tax Status. (i) Each of the Borrower, the Guarantor and
                    ----------
their respective Subsidiaries (a) has made or filed all federal, state and local
income and all other tax returns, reports and declarations required by any
jurisdiction to which it is subject, (b) has paid all taxes and other
governmental assessments and charges shown or determined to be due on such
returns, reports and declarations, except those being contested in good 

                                      -41-
<PAGE>
 
faith and by appropriate proceedings, and (c) has set aside on its books
provisions reasonably adequate for the payment of all taxes for periods
subsequent to the periods to which such returns, reports or declarations apply,
and (ii) there are no unpaid taxes in any material amount claimed to be due by
the taxing authority of any jurisdiction, and the respective officers of the
Borrower and the Guarantor and their respective Subsidiaries know of no basis
for any such claim.

           (S)7.11  No Event of Default. No Default or Event of Default has
                    -------------------
occurred and is continuing.

           (S)7.12. Investment Company Acts. None of the Borrower, the
                    -----------------------
Guarantor or any of their respective Subsidiaries is an "investment company", or
an "affiliated company" or a "principal underwriter" of an "investment company",
as such terms are defined in the Investment Company Act of 1940.

           (S)7.13. Absence of UCC Financing Statements, Etc. Except for
                    ----------------------------------------
Permitted Liens and except to the extent the failure or breach of such
representation and warranty constitutes a Non-Material Breach, there is no
financing statement, security agreement, chattel mortgage, real estate mortgage,
equipment lease, financing lease, option, encumbrance or other document filed or
recorded with any filing records, registry, or other public office, that
purports to cover, affect or give notice of any present or possible future lien
or encumbrance on, or security interest in, any Borrowing Base Property. Neither
the Borrower nor the Guarantor has pledged or granted any lien on or security
interest in or otherwise encumbered or transferred any of their respective
interests in any Subsidiary who is a Borrower (including in the case of the
Guarantor, its interests in BPLP), unless such pledge, lien or security interest
relates only to a Borrower other than BPLP and is a Non-Material Breach.

           (S)7.14. Absence of Liens. The Borrower or the Guarantor is the
                    ----------------
owner of or the holder of a ground leasehold interest in the Borrowing Base
Properties free from any Lien, except for Permitted Liens.

           (S)7.15. Certain Transactions.  [Intentionally Omitted.]
                    --------------------

           (S)7.16. Employee Benefit Plans; Multiemployer Plans; Guaranteed
                    -------------------------------------------------------
Pension Plans. Except as disclosed in the SEC Filings, none of the Borrower, the
- -------------
Guarantor nor any ERISA Affiliate maintains or contributes to any Employee
Benefit Plan, Multiemployer Plan or Guaranteed Pension Plan.

           (S)7.17. Regulations U and X. No portion of any Loan is to be
                    -------------------
used, and no portion of any Letter of Credit is to be obtained, for the purpose
of purchasing or carrying any "margin security" or "margin stock" as such terms
are used in Regulations U and X of the Board of Governors of the Federal Reserve
System, 12 C.F.R. Parts 221 and 224.

           (S)7.18. Environmental Compliance. The Borrower has caused Phase I
                    ------------------------
and other environmental assessments (collectively, the "Environmental Reports")
to be conducted 

                                      -42-
<PAGE>
 
and/or taken other steps to investigate the past and present environmental
condition and usage of the Real Estate Assets. Based upon such Environmental
Reports, to the Borrower's knowledge, except as identified in such Environmental
Reports, the Borrower makes the following representations and warranties:

                     (a)       None of the Borrower, its Subsidiaries, any
Guarantor or any operator of the Real Estate Assets or any portion thereof, or
any operations thereon is in material violation, or alleged material violation,
of any judgment, decree, order, law, license, rule or regulation pertaining to
environmental matters, including without limitation, those arising under the
Resource Conservation and Recovery Act ("RCRA"), the Comprehensive Environmental
Response, Compensation and Liability Act of 1980 as amended ("CERCLA"), the
Superfund Amendments and Reauthorization Act of 1986 ("SARA"), the Federal Clean
Water Act, the Federal Clean Air Act, the Toxic Substances Control Act, or any
state or local statute, regulation, ordinance, order or decree relating to
health, safety or the environment (hereinafter "Environmental Laws"), which
violation or alleged violation has, or its remediation would have, by itself or
when aggregated with all such other violations or alleged violations, a material
adverse effect on the business, assets or financial condition of the Borrower
and its Subsidiaries, taken as a whole, or constitutes a Disqualifying
Environmental Event with respect to any of the Borrowing Base Properties.

                     (b)       None of the Borrower, any Guarantor or any of
their respective Subsidiaries has received written notice from any third party,
including, without limitation, any federal, state or local governmental
authority, (i) that it has been identified by the United States Environmental
Protection Agency ("EPA) as a potentially responsible party under CERCLA with
respect to a site listed on the National Priorities List, 40 C.F.R. Part 300
Appendix B (1986), (ii) that any hazardous waste, as defined by 42 U.S.C. 
(S)9601(5), any hazardous substances as defined by 42 U.S.C. (S)9601(14), any
pollutant or contaminant as defined by 42 U.S.C. (S)9601(33) or any toxic
substances, oil or hazardous materials or other chemicals or substances
regulated by any Environmental Laws ("Hazardous Substances") which it has
generated, transported or disposed of have been found at any site at which a
federal, state or local agency or other third party has conducted or has ordered
that the Borrower, any Guarantor or any of their respective Subsidiaries conduct
a remedial investigation, removal or other response action pursuant to any
Environmental Law, or (iii) that it is or shall be a named party to any claim,
action, cause of action, complaint, or legal or administrative proceeding (in
each case, contingent or otherwise) arising out of any third party's incurrence
of costs, expenses, losses or damages of any kind whatsoever in connection with
the release of Hazardous Substances, which event described in any such notice
would have a material adverse effect on the business, assets or financial
condition of the Borrower and its Subsidiaries, taken as a whole, or constitutes
a Disqualifying Environmental Event with respect to any of the Borrowing Base
Properties.

                     (c)       (i) No portion of the Real Estate Assets has been
used for the handling, processing, storage or disposal of Hazardous Substances
except in material accordance with applicable Environmental Laws; and no
underground tank or other 

                                      -43-
<PAGE>
 
underground storage receptacle for Hazardous Substances is located on any
portion of any Real Estate Assets except in material accordance with applicable
Environmental Laws, (ii) in the course of any activities conducted by the
Borrower, the Guarantor, their respective Subsidiaries or the operators of their
respective properties or any ground or space tenants on any Real Estate Asset,
no Hazardous Substances have been generated or are being used on such Real
Estate Asset except in material accordance with applicable Environmental Laws,
(iii) there has been no present or, to the best of Borrower's knowledge, past
releasing, spilling, leaking, pumping, pouring, emitting, emptying, discharging,
injecting, escaping, disposing or dumping (a "Release") or threatened Release of
Hazardous Substances on, upon, into or from the Real Estate Assets in violation
of applicable Environmental Laws, (iv) to the best of Borrower's knowledge,
there have been no Releases in violation of applicable Environmental Laws upon,
from or into any real property in the vicinity of any of the Real Estate Assets
which, through soil or groundwater contamination, may have come to be located on
such Real Estate Asset, and (v) to the best of Borrower's Knowledge, any
Hazardous Substances that have been generated on any of the Real Estate Assets
during ownership thereof by the Borrower, the Guarantor their respective
Subsidiaries or the operations of their respective properties have been
transported off-site only in compliance with all applicable Environmental Laws;
any of which events described in clauses (i) through (v) above would have a
material adverse effect on the business, assets or financial condition of BPLP,
the Guarantor, or taken as a whole, the BP Group, or constitutes a Disqualifying
Environmental Event with respect to any of the Borrowing Base Properties.
Notwithstanding that the representations contained herein are limited to the
knowledge of the Borrower, any such limitation shall not affect the covenants
specified in (S)8.11 or elsewhere in this Agreement.

                  (d)       None of the Borrower, the Guarantor or any of the
Real Estate Assets is subject to any applicable Environmental Law requiring the
performance of Hazardous Substances site assessments, or the removal or
remediation of Hazardous Substances, or the giving of notice to any governmental
agency or the recording or delivery to other Persons of an environmental
disclosure document or statement, by virtue of the transactions set forth herein
and contemplated hereby, or as a condition to the effectiveness of any other
transactions contemplated hereby.

      (S)7.19.    Subsidiaries. Schedule 7.19 sets forth, as of the Closing
                  ------------  -------------
Date, all of the respective Subsidiaries of BPLP, each other Borrower and the
Guarantor.

      (S)7.20.    Loan Documents. All of the representations and warranties
                  --------------
by or on behalf of the Borrower and the Guarantor and their respective
Subsidiaries made in this Agreement and in the other Loan Documents or any
document or instrument delivered to the Agent or the Banks pursuant to or in
connection with any of such Loan Documents are true and correct in all material
respects and do not include any untrue statement of a material fact or omit to
state a material fact required to be stated or necessary to make such
representations and warranties not materially misleading.

                                      -44-
<PAGE>
 
           (S)7.21. REIT Status. The Guarantor has not taken any action that
                    -----------
would prevent it from maintaining its qualification as a REIT for its tax year
ended December 31, 1997 or from maintaining such qualification at all times
during the term of the Loans.

           (S)7.22 Initial Public Offering Registration Statement.
                   ----------------------------------------------

           (a) A registration statement on Form S-11 (File No. 333-25279) with
respect to the Common Stock (as defined in such registration statement) has been
prepared by the Guarantor in conformity with the requirements of the Securities
Act of 1933, as amended (the "Act"), and the rules and regulations (the "Rules
and Regulations") of the Securities and Exchange Commission (the "SEC" or the
"Commission") thereunder; and has been filed with the Commission. The Guarantor
has prepared and has filed amendments to such registration statement, which
amendments have been similarly prepared. There has been delivered to the Agent
copies of such registration statement and amendments, together with copies of
each exhibit filed therewith. The Guarantor has also prepared a related
preliminary prospectus, a copy of which has also been provided to the Agent. The
Guarantor has also filed with the Commission (or will timely file) one of the
following: (i) prior to effectiveness of such registration statement, a further
amendment thereto, including the form of final prospectus, or (ii) a final
prospectus in accordance with Rules 430A and 424(b) of the Rules and
Regulations. As filed, such amendment and form of final prospectus, or such
final prospectus, include all Rule 430A Information.

           The term "Registration Statement" as used in this Agreement means the
above registration statement at the time such registration statement became
effective and, in the event any post-effective amendment thereto became
effective, shall also mean such registration statement as so amended; provided,
                                                                      --------
however, that such term shall also include all Rule 430A Information deemed to
- -------
be included in such registration statement at the time such registration
statement became effective as provided by Rule 430A of the Rules and
Regulations. The term "Preliminary Prospectus" means any preliminary prospectus
referred to in the preceding paragraph and any preliminary prospectus included
in the Registration Statement at the time it became effective that omits Rule
430A Information. The term "Prospectus" as used in this Agreement shall mean the
prospectus relating to the Common Stock in the form in which it is first filed
with the Commission pursuant to Rule 424(b) of the Rules and Regulations or, if
no filing pursuant to Rule 424(b) of the Rules and Regulations is required,
means the form of final prospectus included in the Registration Statement at the
time such registration statement became effective. The term "Rule 430A
Information" means information with respect to the Common Stock and the offering
thereof permitted to be omitted from the Registration Statement when it became
effective pursuant to Rule 430A of the Rules and Regulations.

           (b) The Commission has not issued any order preventing or suspending
the use of any Preliminary Prospectus, and each Preliminary Prospectus has
conformed in all material respects to the requirements of the Act and the Rules
and Regulations and, as of its date, has not included any untrue statement of a
material fact or omitted to state a material fact necessary to make the
statements therein, in the light of the circumstances under which they were
made, not misleading; as of the Closing Date, the Registration 

                                      -45-
<PAGE>
 
Statement has become effective and the Registration Statement and the
Prospectus, and any amendments or supplements thereto, contain all material
statements and information required to be included therein by the Act and the
Rules and Regulations and in all material respects conform to the requirements
of the Act and the Rules and Regulations, and neither the Registration Statement
nor the Prospectus, nor any amendment or supplement thereto, include any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading.

           (S)8.   AFFIRMATIVE COVENANTS OF THE BORROWER AND THE GUARANTOR.
                   -------------------------------------------------------
The Borrower for itself and on behalf of the Guarantor and their respective
Subsidiaries (if and to the extent expressly included in Subsections contained
in this Section) covenants and agrees that, so long as any Loan, Letter of
Credit or Revolving Credit Note is outstanding or the Banks have any obligation
to make any Loans or any Bank has any obligation to issue, extend or renew any
Letters of Credit:

           (S)8.1. Punctual Payment. The Borrower will duly and punctually
                   ----------------
pay or cause to be paid the principal and interest on the Loans and all
interest, fees, charges and other amounts provided for in this Agreement and the
other Loan Documents, all in accordance with the terms of this Agreement and the
Revolving Credit Notes, and the other Loan Documents.

           (S)8.2. Maintenance of Office. Each of the Borrower and the
                   ---------------------
Guarantor will maintain its chief executive office in Boston, Massachusetts, or
at such other place in the United States of America as each of them shall
designate in Schedule 2 or otherwise upon written notice to the Agent to be
             ----------
delivered within fifteen (15) days of any change of chief executive office,
where, subject to (S)22, notices, presentations and demands to or upon the
Borrower and the Guarantor, as the case may be, in respect of the Loan Documents
may be given or made.

           (S)8.3. Records and Accounts. Each of the Borrower and the
                   --------------------
Guarantor will (a) keep, and cause each of its Subsidiaries to keep, true and
accurate records and books of account in which full, true and correct entries in
all material respects will be made in accordance with GAAP and (b) maintain
adequate accounts and reserves for all taxes (including income taxes),
contingencies, depreciation and amortization of its properties and the
properties of its Subsidiaries; all of such reserves may be unfunded.

           (S)8.4. Financial Statements, Certificates and Information. The
                   --------------------------------------------------  
Borrower will deliver and cause the Guarantor to deliver (as applicable) to the
Agent (with copies to the Agent for each Bank):

                   (a)   as soon as practicable, but in any event not later
than ninety (90) days after the end of each fiscal year of the Guarantor, the
audited consolidated balance sheet of the Guarantor and its Subsidiaries at the
end of such year, and the related audited consolidated statements of income,
changes in shareholder's equity and cash flows for the year then ended, in each
case, setting forth in comparative form the figures for the 

                                      -46-
<PAGE>
 
previous fiscal year and all such statements to be in reasonable detail,
prepared in accordance with GAAP, and, in each case, accompanied by an auditor's
report prepared without qualification by the Accountants; together with a
written statement from such Accountants to the effect that they have read a copy
of this Agreement, and that, in making the examination necessary to said
certification, they have obtained no knowledge of any Default or Event of
Default under (S)9 or (S)10 or otherwise under the provisions of this Agreement
relating to the financial condition of the Guarantor or any of its Subsidiaries,
or of any facts or circumstances that would cause the Guarantor not to continue
to qualify as a REIT for federal income tax purposes, or, if such Accountants
shall have obtained knowledge of any then existing Default, Event of Default or
such facts or circumstances, they shall make disclosure thereof in such
statement;

                     (b)       as soon as practicable, but in any event not
later than forty-five (45) days after the end of each of its March 31, June 30
and September 30 fiscal quarters, copies of the unaudited consolidated balance
sheet of the Guarantor and its Subsidiaries as at the end of such quarter, and
the related unaudited consolidated statements of income, changes in
shareholders' equity and cash flows for the portion of the Guarantor's fiscal
year then elapsed, all in reasonable detail and prepared in accordance with GAAP
(which may be provided by inclusion in the Form 10-Q of the Guarantor filed with
the SEC for such period provided pursuant to clause (i) below), together with a
certification by the principal financial or accounting officer of the Borrower
and the Guarantor that the information contained in such financial statements
fairly presents the financial position of the Guarantor and its Subsidiaries on
the date thereof (subject to year-end adjustments none of which shall be
materially adverse);

                     (c)       Upon the request of the Agent and as soon as
practicable, but in any event not later than ninety (90) days after the end of
each of its fiscal years, statements of Net Operating Income and outstanding
Indebtedness as at the end of such fiscal year and for the fiscal year then
ended in respect of each Real Estate Asset (including each Borrowing Base
Property), each prepared in accordance with GAAP consistent with the definitions
of Net Operating Income and outstanding Indebtedness used in this Agreement and
a summary rent roll in respect of each Borrowing Base Property, in each case
certified by the chief financial or accounting officer of the Borrower as true
and correct in all material respects;

                     (d)       Upon the request of the Agent and as soon as
practicable, but in any event not later than forty-five (45) days after the end
of each of the fiscal quarters of the Borrower, (1) copies of the unaudited
statements of Net Operating Income and outstanding Indebtedness as at the end of
such quarter and for the portion of the fiscal year then elapsed in respect of
each Real Estate Asset (including each Borrowing Base Property), each prepared
in accordance with GAAP consistent with the definitions of Net Operating Income
and outstanding Indebtedness used in this Agreement and certified by the chief
financial or accounting officer of the Borrower to present fairly the Net
Operating Income and outstanding Indebtedness in respect of each such Real
Estate Asset and (ii) an occupancy analysis in respect of each Real Estate Asset
(including each 

                                      -47-
<PAGE>
 
Borrowing Base Property) certified by the chief financial officer of the
Borrower to be true and complete in all material respects;

                     (e)       simultaneously with the delivery of the financial
statements referred to in subsections (a) and (b) above, a statement in the form
of Exhibit C-2 hereto signed by the chief financial or accounting officer of the
Borrower and (if applicable) reconciliations to reflect changes in GAAP since
the date of such financial statements;

                     (f)       promptly as they become available, a copy of each
report (including any so-called management letters) submitted to the Borrower,
the Guarantor or any of their respective subsidiaries by the Accountants in
connection with each annual audit of the books of the Borrower, the Guarantor or
such Subsidiary by such Accountants or in connection with any interim audit
thereof pertaining to any phase of the business of the Borrower, the Guarantor
or any such Subsidiary;

                     (g)       contemporaneously with (or promptly after) the
filing or mailing thereof, copies of all material of a financial nature sent to
the holders of any Indebtedness of the Borrower (other than the Loans) for
borrowed money, to the extent that the information or disclosure contained in
such material refers to or could reasonably be expected to have a material
adverse effect on the business, assets, financial condition or prospects, or
operations of BPLP, the Guarantor or, taken as a whole, the BP Group;

                     (h)       contemporaneously with the filing or mailing
thereof, copies of all material of a financial nature filed with the SEC or sent
to the stockholders of the Guarantor;

                     (i)       as soon as practicable, but in any event not
later than ninety (90) days after the end of each fiscal year of the Guarantor,
copies of the Form 10-K statement filed by the Guarantor with the SEC for such
fiscal year, and as soon as practicable, but in any event not later than fifty
(50) days after the end of each fiscal quarter of the Guarantor copies of the
Form 10-Q statement filed by the Guarantor with the SEC for such fiscal quarter,
provided that, in either case, if the SEC has granted an extension for the
filing of such statements, the Guarantor shall deliver such statements to the
Agent within ten (10) days after the filing thereof with the SEC;

                     (j)       from time to time such other financial data and
information about the Borrower, the Guarantor, their respective Subsidiaries,
the Real Estate Assets and the Partially-Owned Real Estate Holding Entities as
the Agent or any Bank (through the Agent) may reasonably request, including
without limitation complete rent rolls, existing environmental reports, and
insurance certificates with respect to the Real Estate Assets (including the
Borrowing Base Properties);

                     (k)       in the case of the Borrower and the Guarantor, as
soon as practicable, but in any event not later than ninety (90) days after the
end of each of their respective fiscal years, pro forma projections for the next
three fiscal years;

                                      -48-
<PAGE>
 
                     (l)       together with the financial statements delivered
pursuant to (S)8.4(a), a certification by the chief financial or accounting
officer of the Borrower of the state and federal taxable income of the Guarantor
and its Subsidiaries as of the end of the applicable fiscal year; and

                     (m)       in the event that the definition of "funds from
operations" is revised by the Board of Governors of the National Association of
Real Estate Investment Trusts, a report, certified by the chief financial or
accounting officer of the Borrower, of the "funds from operations" of the
Borrower based on the definition as in effect on the date of this Agreement and
based on the definition as so revised from time to time, which such report shall
be delivered to the Agent (with copies to the Agent for each Bank) with the
financial statements required to be delivered pursuant to (S)8.4(b) above.

              (S)8.5. Notices.
                      -------

                     (a)       Defaults. The Borrower will, and will cause the
                               --------
Guarantor, as applicable, to, promptly after obtaining knowledge of the same,
notify the Agent in writing (with copies to the Agent for each Bank) of the
occurrence of any Default or Event of Default or Non-Material Breach. If any
Person shall give any notice or take any other action in respect of (x) a
claimed Default (whether or not constituting an Event of Default) under this
Agreement or (y) a claimed failure by the Borrower, the Guarantor or any of
their respective Subsidiaries, as applicable, to comply with any term, condition
or provision of or under any note, evidence of Indebtedness, indenture or other
obligation in excess of $10,000,000, individually or in the aggregate, to which
or with respect to which any of them is a party or obligor, whether as principal
or surety, and such failure to comply would permit the holder of such note or
obligation or other evidence of Indebtedness to accelerate the maturity thereof,
which acceleration would have a material adverse effect on BPLP, the Guarantor
or, taken as a whole, the BP Group, the Borrower or Guarantor, as the case may
be, shall forthwith give written notice thereof to the Agent and each of the
Banks, describing the notice or action and the nature of the claimed failure to
comply.

                     (b)       Environmental Events. The Borrower will, and will
                               --------------------
cause the Guarantor to, promptly give notice in writing to the Agent (with
copies to the Agent for each Bank) (i) upon Borrower's or Guarantor's obtaining
knowledge of any material violation (as determined by the Borrower or Guarantor
in the exercise of its reasonable discretion) of any Environmental Law regarding
any Real Estate Asset or Borrower's or Guarantor's operations, (ii) upon
Borrower's or Guarantor's obtaining knowledge of any known Release of any
Hazardous Substance at, from, or into any Real Estate Asset which it reports in
writing or is reportable by it in writing to any governmental authority and
which is material in amount or nature or which could materially affect the value
of such Real Estate Asset, (iii) upon Borrower's or such Guarantor's receipt of
any notice of material violation of any Environmental Laws or of any material
Release of Hazardous Substances in violation of any Environmental Laws or any
matter that may be a Disqualifying Environmental Event with respect to any of
the Borrowing Base Properties, including a notice or claim of liability or
potential responsibility from any 

                                      -49-
<PAGE>
 
third party (including without limitation any federal, state or local
governmental officials) and including notice of any formal inquiry, proceeding,
demand, investigation or other action with regard to (A) Borrower's or such
Guarantor's or any other Person's operation of any Real Estate Asset, (B)
contamination on, from or into any Real Estate Asset, or (C) investigation or
remediation of off-site locations at which Borrower or such Guarantor or any of
its predecessors are alleged to have directly or indirectly disposed of
Hazardous Substances, or (iv) upon Borrower's or such Guarantor's obtaining
knowledge that any expense or loss has been incurred by such governmental
authority in connection with the assessment, containment, removal or remediation
of any Hazardous Substances with respect to which Borrower or such Guarantor or
any Partially-Owned Real Estate Entity may be liable or for which a lien may be
imposed on any Real Estate Asset; any of which events described in clauses (i)
through (iv) above would have a material adverse effect on the business, assets
or financial condition of the Borrower and its Subsidiaries, taken as a whole,
or constitutes a Disqualifying Environmental Event with respect to any of the
Borrowing Base Properties.

                     (c)       Notification of Claims against Borrowing Base
                               ---------------------------------------------
Properties. The Borrower will, and will cause each Subsidiary to, promptly upon
- ----------
becoming aware thereof, notify the Agent in writing (with copies to the Agent
for each Bank) of any setoff, claims, withholdings or other defenses to which
any of the Borrowing Base Properties are subject, which (i) would have a
material adverse effect on (x) the business, assets or financial condition of
BPLP, the Guarantor or, taken as a whole, the BP Group, or (y) the value of any
such Borrowing Base Property, or (ii) with respect to such Borrowing Base
Property, constitute a Disqualifying Environmental Event, a Disqualifying
Structural Event or a Lien subject to the bonding or insurance requirement of
(S)9.2(viii).

                     (d)       Notice of Litigation and Judgments. The Borrower
                               ----------------------------------
will, and will cause the Guarantor and their respective Subsidiaries, to give
notice to the Agent in writing (with copies to the Agent for each Bank) within
fifteen (15) days of becoming aware of any litigation or proceedings threatened
in writing or any pending litigation and proceedings an adverse determination in
which could materially affect BPLP, the Guarantor or taken as a whole, the BP
Group, or any Borrowing Base Property or to which the Borrower, the Guarantor or
any of their respective Subsidiaries is or is to become a party involving an
uninsured claim against the Borrower, the Guarantor or any of their respective
Subsidiaries that could reasonably be expected to have a materially adverse
effect on BPLP, the Guarantor or, taken as a whole, the BP Group, the respective
properties, business, assets, financial condition or prospects or on the value
or operation of the Borrowing Base Properties and stating the nature and status
of such litigation or proceedings. The Borrower will, and will cause each of the
Guarantor and their respective Subsidiaries to, give notice to the Agent and
each of the Banks, in writing, in form and detail reasonably satisfactory to the
Agent and each of the Banks, within ten (10) days of any judgment not covered by
insurance, final or otherwise, against the Borrower, Guarantor or any of such
Subsidiaries in an amount in excess of $1,000,000.

                                      -50-
<PAGE>
 
                     (e)       Acquisition of Real Estate Assets. The Borrower
                               ---------------------------------
shall notify the Agent in writing (with copies to the Agent for each Bank)
within seven (7) days of the acquisition of any Real Estate Asset by the
Borrower, the Guarantor or any other member of the BP Group (whether or not such
acquisition was made with proceeds of the Loans), which notice shall include, at
the Agent's request, with respect to such Real Estate Asset, its address, a
brief description and recent photograph, a rent roll summary, a pro forma and
historic (if available) income statement and a summary of the key business terms
of such acquisition, provided that the failure of the Borrower to provide such
notice to the Agent shall not constitute a Default or Event of Default
hereunder.

                     (f)       Insolvency Events. The Borrower shall notify the
                               -----------------
Agent in writing (with copies to the Agent for each Bank) promptly after the
occurrence of any of the events described in ss.14.1(g) or (h) with respect to
any member of the BP Group other than BPLP and the Guarantor.

              (S)8.6. Existence of Borrower; Maintenance of Properties. The
                      ------------------------------------------------
Borrower will do or cause to be done all things necessary to, and shall,
preserve and keep in full force and effect its respective existence in its
jurisdiction of organization and will do or cause to be done all things
necessary to preserve and keep in full force all of its respective rights and
franchises and those of its respective Subsidiaries each of which in the good
faith judgment of BPLP may be necessary to properly and advantageously conduct
the businesses conducted by it. The Borrower (a) will cause all necessary
repairs, renewals, replacements, betterments and improvements to be made to all
Real Estate Assets owned or controlled by it, all as in the judgment of the
Borrower may be necessary so that the business carried on in connection
therewith may be properly and advantageously conducted at all times, subject to
the terms of the applicable Leases and partnership agreements or other entity
charter documents, and in any event, will keep all of the Real Estate Assets
(for so long as such Real Estate Assets are owned by the Borrower, the Guarantor
or any of their respective Subsidiaries) in a condition consistent with the Real
Estate Assets currently owned or controlled by the Borrower or its Subsidiaries,
(b) will cause all of its other properties and those of its Subsidiaries (to the
extent controlled by the Borrower) used or useful in the conduct of its business
or the business of its Subsidiaries to be maintained and kept in good condition,
repair and working order and supplied with all necessary equipment, and (c)
will, and will cause each of its Subsidiaries to continue to engage primarily in
the businesses now conducted by it and in related businesses, all of the
foregoing to the extent necessary to comply with the other terms and conditions
set forth in this Agreement, and in the case of clauses (a) and (b) above,
except to the extent that the failure to comply with the provisions thereof
constitutes a Non-Material Breach.

             (S)8.7. Existence of Guarantor; Maintenance of REIT Status of
                     -----------------------------------------------------
Guarantor; Maintenance of Properties. The Borrower will cause the Guarantor to
- ------------------------------------
do or cause to be done all things necessary to preserve and keep in full force
and effect the Guarantor's existence as a Delaware corporation. The Borrower
will cause 

                                      -51-
<PAGE>
 
the Guarantor at all times to maintain its status as a REIT and not to take any
action which could lead to its disqualification as a REIT. Without limitation of
(S)9.3(f) hereof, the Borrower will cause the Guarantor not to engage in any
business other than the business of acting as a REIT and serving as the general
partner and limited partner of the Borrower, as a member, partner or stockholder
of other Persons and matters directly relating thereto and as a Guarantor, and
shall cause the Guarantor to conduct all or substantially all of its business
operations through the Borrower or through subsidiary partnerships or other
entities in which the Borrower owns at least 99% of the economic interests. The
Borrower will cause the Guarantor (a) to cause all of its properties and those
of its Subsidiaries used or useful in the conduct of its business or the
business of its Subsidiaries to be maintained and kept in good condition, repair
and working order (including, without limitation, that all Real Estate Assets
will be maintained in a condition consistent with the Real Estate Assets
currently owned or controlled by the Guarantor or its Subsidiaries), and
supplied with all necessary equipment, (b) to cause to be made all necessary
repairs, renewals, replacements, betterments and improvements thereof, all as in
the judgment of the Guarantor may be necessary so that the business carried on
in connection therewith may be properly and advantageously conducted at all
times and (c) to cause each of its Subsidiaries to continue to engage primarily
in the businesses now conducted by it and in related businesses, in each case
under clauses (a), (b) and (c) above to the extent, in the good faith judgment
of the Guarantor, necessary to properly and advantageously conduct the
businesses being conducted by it.

              (S)8.8. Insurance. The Borrower will, and will cause the Guarantor
                      ---------
to, maintain with respect to its properties, and will cause each of its
Subsidiaries to maintain with financially sound and reputable insurers,
insurance with respect to such properties and its business against such
casualties and contingencies as shall be in accordance with the general
practices of businesses engaged in similar activities in similar geographic
areas and in amounts, containing such terms, in such forms and for such periods
as may be reasonable and prudent, unless any failure to do so does not relate to
BPLP or the Guarantor and is a Non-Material Breach.

              (S)8.9. Taxes. The Borrower will, and will cause the Guarantor and
                      -----
each of their respective Subsidiaries to, pay or cause to be paid real estate
taxes, other taxes, assessments and other governmental charges against the Real
Estate Assets before the same become delinquent and will duly pay and discharge,
or cause to be paid and discharged, before the same shall become overdue, all
taxes, assessments and other governmental charges imposed upon its sales and
activities, or any part thereof, or upon the income or profits therefrom, as
well as all claims for labor, materials, or supplies that if unpaid might by law
become a lien or charge upon any of the Real Estate Assets, unless any failure
to do so does not relate to BPLP or the Guarantor and is a Non-Material Breach;
provided that any such tax, assessment, charge, levy or claim need not be paid
if the validity or amount thereof shall currently be contested in good faith by
appropriate proceedings and if the Borrower or the Guarantor shall have set
aside on its books adequate reserves with respect thereto; and provided further
that the Borrower or the Guarantor will pay all such taxes, assessments,
charges, levies or claims forthwith prior to the consummation of proceedings to
foreclose any lien that may have attached as security therefor. Promptly upon
request by the Agent if required for bank regulatory compliance purposes or
similar bank purposes, the Borrower will provide evidence of the 

                                      -52-
<PAGE>
 
payment of real estate taxes, other taxes, assessments and other governmental
charges against the Real Estate Assets in the form of receipted tax bills or
other form reasonably acceptable to the Agent, or evidence of the existence of
applicable contests as contemplated herein.

              (S)8.10. Inspection of Properties and Books. The Borrower will,
                       ----------------------------------
and will cause the Guarantor to, permit the Agent or any of the Banks' other
designated representatives upon no less than 24 hours notice (which notice may
be given orally or in writing), to visit and inspect any of the properties of
the Borrower, the Guarantor or any of their respective Subsidiaries to examine
the books of account of the Borrower, the Guarantor and their respective
Subsidiaries (and to make copies thereof and extracts therefrom) and to discuss
the affairs, finances and accounts of the Borrower, the Guarantor and their
respective Subsidiaries with, and to be advised as to the same by, its officers,
all at such reasonable times and intervals as the Agent may reasonably request;
provided that, so long as no Event of Default has occurred and is continuing,
- --------
the Borrower shall only be responsible for the costs and expenses incurred by
the Agent in connection with such inspections. The Agent and each Bank agrees to
keep any non-public information delivered or made available by the Borrower to
it confidential from anyone other than persons employed or retained by the Agent
or such Bank who are or are expected to become engaged in evaluating, approving,
structuring or administering the Loans; provided that nothing herein shall
                                        --------
prevent the Agent or any Bank from disclosing such information (i) to any other
Bank, (ii) to any other person if reasonably incidental to the administration of
the Loans, (iii) upon the order of any court or administrative agency, (iv) upon
the request or demand of any regulatory agency or authority, (v) which has been
publicly disclosed other than as a result of a disclosure by the Agent or any
Bank which is not permitted by this Agreement, (vi) in connection with any
litigation to which the Agent, any Bank, or their respective Affiliates may be a
party, (vii) to the extent reasonably required in connection with the exercise
of any remedy hereunder, (viii) to the Agent's or such Bank's Affiliates, legal
counsel and independent auditors, and (ix) to any actual or proposed participant
or Eligible Assignee of all or part of its rights hereunder.

              (S)8.11. Compliance with Laws, Contracts, Licenses, and Permits.
                       ------------------------------------------------------
The Borrower will, and will cause the Guarantor to, comply with, and will cause
each of their respective Subsidiaries to comply with (a) all applicable laws and
regulations now or hereafter in effect wherever its business is conducted,
including, without limitation, all Environmental Laws and all applicable federal
and state securities laws, (b) the provisions of its partnership agreement or
corporate charter and other charter documents and by-laws, as applicable, (c)
all material agreements and instruments to which it is a party or by which it or
any of its properties may be bound (including the Real Estate Assets and the
Leases) and (d) all applicable decrees, orders, and judgments, unless such non-
compliance does not relate to BPLP or the Guarantor and constitutes a Non-
Material Breach. If at any time while any Loan or Revolving Credit Note or
Letter of Credit is outstanding or the Banks have any obligation to make Loans
or issue Letters of Credit hereunder, any Permit shall become necessary or
required in order that the Borrower may fulfill any of its obligations
hereunder, the Borrower and the Guarantor and their respective Subsidiaries will
immediately take or cause to be taken all reasonable steps 

                                      -53-
<PAGE>
 
within the power of the Borrower or the Guarantor, as applicable, to obtain such
Permit and furnish the Agent with evidence thereof.

              (S)8.12. Use of Proceeds. Subject at all times to the other
                       ---------------
provisions this Agreement, the Borrower will use the proceeds of the Loans
solely for working capital and general corporate purposes, including, without
limitation, in connection with the acquisition, rehabilitation and development
of Permitted Properties and the acquisition of Mortgages in accordance with the
provisions of this Agreement.

              (S)8.13. Addition of Borrowing Base Property. Prior to the
                       -----------------------------------
addition of any Real Estate Asset to the Borrowing Base as a Borrowing Base
Property, the Borrower shall promptly deliver to the Agent (i) the Joinder
Documents (including the documents, instruments, certificates and agreements
required thereby). Upon satisfaction of the requirements of this (S)8.13, and
subject to the compliance of any such additional Borrowing Base Property with
the Borrowing Base Conditions, such Real Estate Asset shall be included as a
Borrowing Base Property.

              (S)8.14. Additional Borrowers; Solvency of Borrowers; Removal
                       ----------------------------------------------------
of Borrowers.
- ------------

                     (a)       If, after the Closing Date, BPLP wishes to
designate as a Borrowing Base Property a Real Estate Asset that otherwise
qualifies as a Borrowing Base Property but is owned or ground-leased by a Person
other than the Borrower, BPLP shall cause such Person (which Person must be a
Wholly-owned Subsidiary) to become a party to this Agreement and the other
applicable Loan Documents prior to such Real Estate Asset becoming a Borrowing
Base Property hereunder. The liability of each Borrower which is from time to
time a Borrower hereunder shall be joint and several with all other Borrowers
for all Obligations for so long as such Borrower is a Borrower hereunder
(provided that BPLP shall at all times be a Borrower hereunder). At any time and
 --------
from time to time but only for so long as no Default or Event of Default shall
then exist, BPLP may notify Agent, in writing (each, a "Release Notice"), that
one (1) or more Borrowing Base Properties are to be removed from the Borrowing
Base. Such Release Notice shall be accompanied by a Certificate of Compliance in
the form of Exhibit C-4, evidencing compliance. Immediately upon receipt of such
            -----------
Release Notice and Certificate of Compliance, such Borrowing Base Properties
(each, a "Released Property") shall be removed from the Borrowing Base and any
Wholly-owned Subsidiary which is the owner of a Released Property and which is
then a Borrower (other than BPLP) hereunder shall be released from its
obligations hereunder (including the Obligations), provided, however, that any
                                                   --------  -------
such release shall only be effective as to Obligations arising after the
applicable Release Notice (and the Certificate of Compliance evidencing
compliance) is received by Agent. BPLP will not permit any Borrower (other than
BPLP) that owns or ground leases any Borrowing Base Property to have any
Subsidiaries unless such Subsidiary's business, obligations and undertakings are
exclusively related to the business of such Borrower.

                                      -54-
<PAGE>
 
                      (b)       Each Borrower and the Guarantor shall remain
solvent at all times, unless such failure to remain solvent does not relate to
BPLP or the Guarantor and is a Non-Material Breach.

              (S)8.15. Further Assurances. The Borrower will, and will cause the
                       ------------------
Guarantor to, cooperate with, the Agent and the Banks and execute such further
instruments and documents as the Banks or the Agent shall reasonably request to
carry out to their satisfaction the transactions contemplated by this Agreement
and the other Loan Documents.

           8.16. Interest Rate Protection. For any period of time during which
                 ------------------------
the outstanding balance of the Revolving Credit Loans and Letters of Credit
exceeds $200,000,000 for more than 60 consecutive days, the Borrower shall, upon
the Agent's reasonable written request (each, an "Agent Notice"), maintain in
effect interest rate protection arrangements to reduce the Borrower's interest
rate risk on the amounts in excess of such $200,000,000 balance by means of
hedging techniques or vehicles such as interest rate swaps, interest rate caps,
interest rate corridors or interest rate collars, in each case to be capped at a
rate reasonably satisfactory to the Agent and the Majority Banks and otherwise
in form and substance reasonably satisfactory to the Agent. Notwithstanding the
foregoing, Borrower shall be considered to be in compliance with the
requirements set forth above if, within ten (10) days after Borrower's receipt
of Agent's written request, Borrower provides evidence reasonably satisfactory
to Agent of Borrower's intent (together with a proposed plan) to reduce such
outstanding amounts under the Revolving Credit Loans and Letters of Credit to an
amount less than $200,000,000 during the sixty (60) day period following the
date of the Agent's written request. Once obtained, the Borrower shall maintain
such arrangements in full force and effect as provided therein, and shall not,
without Unanimous Bank Approval, modify, terminate, or transfer such
arrangements during the period in which the outstanding balance of the Revolving
Credit Loans and Letters of Credit remains in excess of $200,000,000 with
respect to any specific related Agent Notice. The Borrower may, at its option,
enter into additional interest rate protection arrangements permitted pursuant
to (S)9.3.

              (S)8.17. Environmental Indemnification. The Borrower covenants and
                       -----------------------------
agrees that it will indemnify and hold the Agent and each Bank, and each of
their respective Affiliates, harmless from and against any and all claims,
expense, damage, loss or liability incurred by the Agent or any Bank (including
all reasonable costs of legal representation incurred by the Agent or any Bank,
but excluding, as applicable, for the Agent or a Bank any claim, expense,
damage, loss or liability as a result of the gross negligence or willful
misconduct of the Agent or such Bank or any of their respective Affiliates)
relating to (a) any Release or threatened Release of Hazardous Substances on any
Real Estate Asset; (b) any violation of any Environmental Laws with respect to
conditions at any Real Estate Asset or the operations conducted thereon; (c) the
investigation or remediation of off-site locations at which the Borrower, the
Guarantor or any of their respective Subsidiaries or their predecessors are
alleged to have directly or indirectly disposed of Hazardous Substances; or (d)
any action, suit, proceeding or 

                                      -55-
<PAGE>
 
investigation brought or threatened with respect to any Hazardous Substances
relating to Real Estate Assets (including, but not limited to, claims with
respect to wrongful death, personal injury or damage to property). It is
expressly acknowledged by the Borrower that this covenant of indemnification
shall survive the payment of the Loans and shall inure to the benefit of the
Agent and the Banks and their respective Affiliates, their respective
successors, and their respective assigns under the Loan Documents permitted
under this Agreement.

              (S)8.18. Response Actions. The Borrower covenants and agrees that
                       ----------------
if any Release or disposal of Hazardous Substances shall occur or shall have
occurred on any Real Estate Asset owned directly or indirectly by the Borrower
or the Guarantor, in violation of applicable Environmental Laws, the Borrower
will cause the prompt containment and removal of such Hazardous Substances and
remediation of such wholly-owned Real Estate Asset as necessary to comply with
all Environmental Laws.

              (S)8.19. Environmental Assessments. If the Agent in its good faith
                       -------------------------
judgment, after discussion with the Borrower and review of any environmental
reports provided by the Borrower, has reasonable grounds to believe that a
Disqualifying Environmental Event has occurred with respect to any one or more
of the Borrowing Base Properties, whether or not a Default or an Event of
Default shall have occurred, the Agent may, from time to time, for the purpose
of assessing and determining whether a Disqualifying Environmental Event has in
fact occurred, cause the Borrower to obtain one or more environmental
assessments or audits of such Borrowing Base Property prepared by a
hydrogeologist, an independent engineer or other qualified consultant or expert
approved by the Agent to evaluate or confirm (i) whether any Hazardous
Substances are present in the soil or water at such Borrowing Base Property and
(ii) whether the use and operation of such Borrowing Base Property complies with
all Environmental Laws. Environmental assessments may include without limitation
detailed visual inspections of such Borrowing Base Property including, without
limitation, any and all storage areas, storage tanks, drains, dry wells and
leaching areas, and, if and to the extent reasonable, appropriate and required
pursuant to applicable Environmental Laws, the taking of soil samples, surface
water samples and ground water samples, as well as such other investigations or
analyses as the Agent deems appropriate. All such environmental assessments
shall be at the sole cost and expense of the Borrower; provided, however, the
Agent may not require environmental assessments at the Borrower's expense, with
respect to any Borrowing Base Property, more frequently than upon the occurrence
of a Release on any Borrowing Base Property.

              (S)8.20. Employee Benefit Plans.
                       ----------------------

                       (a)       Notice. The Borrower will, and will cause the
                                 ------
Guarantor to, notify the Agent (with copies to the Agent for each Bank) within a
reasonable period after the establishment of any Employee Benefit Plan or
Guaranteed Pension Plan by any of them or any of their respective ERISA
Affiliates other than those disclosed in the SEC Filings and no Borrower will,
or will permit the Guarantor to, establish any Employee Benefit Plan,
Multiemployer Plan or Guaranteed Pension Plan which could reasonably be 

                                      -56-
<PAGE>
 
expected to have a material adverse effect on BPLP, the Guarantor or, taken as a
whole, the BP Group.

                     (b)       In General. Each Employee Benefit Plan maintained
                               ----------
by the Borrower, the Guarantor or any of their respective ERISA Affiliates will
be operated in compliance in all material respects with the provisions of ERISA
and, to the extent applicable, the Code, including but not limited to the
provisions thereunder respecting prohibited transactions.

                     (c)       Terminability of Welfare Plans. With respect to
                               ------------------------------
each Employee Benefit Plan maintained by the Borrower, the Guarantor or any of
their respective ERISA Affiliates which is an employee welfare benefit plan
within the meaning of (S)3(l) or (S)3(2)(B) of ERISA, the Borrower, the
Guarantor, or any of their respective ERISA Affiliates, as the case may be, has
the right to terminate each such plan at any time (or at any time subsequent to
the expiration of any applicable bargaining agreement) without liability other
than liability to pay claims incurred prior to the date of termination.

                     (d)       Unfunded or Underfunded Liabilities. The Borrower
                               -----------------------------------
will not, and will not permit the Guarantor to, at any time, have accruing or
accrued unfunded or underfunded liabilities with respect to any Employee Benefit
Plan, Guaranteed Pension Plan or Multiemployer Plan, or permit any condition to
exist under any Multiemployer Plan that would create a withdrawal liability,
which such liability could, individually or in the aggregate, reasonably be
expected to have a material adverse effect on BPLP, the Guarantor or, taken as a
whole, the BP Group.

              (S)8.21. No Amendments to Certain Documents. The Borrower will
                       ----------------------------------
not, and will not permit the Guarantor to, at any time cause or permit its
certificate of limited partnership, agreement of limited partnership (including
without limitation the Agreement of Limited Partnership of the Borrower,
articles of incorporation, by-laws, operating agreement or other charter
documents, as the case may be, to be modified, amended or supplemented in any
respect whatever, without (in each case) the express prior written consent or
approval of the Agent, if such changes would affect the Guarantor's REIT status
or otherwise materially adversely affect the rights of the Agent and the Banks
hereunder or under any other Loan Document.

              (S)8.22.    [Intentionally Omitted.]

              (S)9.   CERTAIN NEGATIVE COVENANTS OF THE BORROWER AND THE
                      --------------------------------------------------
GUARANTOR. The Borrower for itself and on behalf of the Guarantor covenants and
- ---------
agrees that, so long as any Loan, Letter of Credit or Revolving Credit Note is
outstanding or any of the Banks has any obligation to make any Loans or any Bank
has any obligation to issue, extend or renew any Letters of Credit:

                                      -57-
<PAGE>
 
           (S)9.1.     Restrictions on Liabilities.
                       ---------------------------

           The Borrower and the Guarantor may, and may permit their respective
Subsidiaries to, create, incur, assume, guarantee or be or remain liable for,
contingently or otherwise, any Liabilities other than the specific Liabilities
which are prohibited under this (S)9.1 and with respect to which Liabilities
each of the Borrower and the Guarantor will not, and will not permit any
Subsidiary to, create, incur, assume, guarantee or be or remain liable for,
contingently or otherwise, singularly or in the aggregate as follows:

                     (a)       Unsecured Indebtedness (excluding the
Obligations) which is incurred under a revolving credit facility with a
commercial bank, trust company, or savings and loan association, provided that,
                                                                 --------
in the event the Borrower acquires a Real Estate Asset with respect to which
there is any such unsecured Indebtedness, the Borrower shall have a period of 90
days in which to repay such Indebtedness in full;

                     (b)       Indebtedness which would result in a Default or
Event of Default under (S)10 hereof,

                     (c)       An aggregate amount in excess of $10,000,000 at
any one time in respect of taxes, assessments, governmental charges or levies
and claims for labor, materials and supplies (other than in respect of
properties owned by Partially-Owned Real Estate Holding Entities) for which
payment therefor is required to be made in accordance with the provisions of
(S)7.9 and such payment is due and delinquent and which is not being contested
diligently and in good faith; and

                     (d)       An aggregate amount in excess of $10,000,000 at
any one time in respect of uninsured judgments or awards, with respect to which
the applicable periods for taking appeals have expired, or with respect to which
final and unappealable judgments or awards have been rendered, and such
judgments or awards remain unpaid for more than thirty (30) days.

           The terms and provisions of this (S)9.1 are in addition to, and not
in limitation of, the covenants set forth in (S)10 of this Agreement.

           Without limiting the foregoing, but subject to the other provisions
of this Agreement (including without limitation (S)10 hereof), Indebtedness
Without Recourse to any of the Credit Parties or any of their respective assets
other than their respective interests in the Real Estate Assets that are subject
to such Indebtedness Without Recourse is not restricted.

           Notwithstanding anything contained herein to the contrary, the
Borrower and the Guarantors will not, and will not permit any Subsidiary to,
incur any Indebtedness for borrowed money in any single transaction which
exceeds $50,000,000 in the aggregate unless the Borrower shall have delivered a
compliance certificate in the form of Exhibit C-3 hereto to the Agent evidencing
                                      -----------
covenant compliance at the time of delivery of the certificate and on a
pro-forma basis after giving effect to such proposed Indebtedness.

                                      -58-
<PAGE>
 
           (S)9.2. Restrictions on Liens, Etc. None of the Borrower, the
                   --------------------------
Guarantor and any Wholly-owned Subsidiary will: (a) create or incur or suffer to
be created or incurred or to exist any lien, mortgage, pledge, attachment,
security interest or other rights of third parties of any kind upon any of the
Borrowing Base Properties, whether now owned or hereafter acquired (but only for
so long as they remain Borrowing Base Properties), or upon the income or profits
therefrom; (b) acquire, or agree or have an option to acquire, any property or
assets upon conditional sale or other title retention or purchase money security
agreement, device or arrangement in connection with the operation of the
Borrowing Base Properties; (c) suffer to exist for a period of more than thirty
(30) days, with respect to the Borrowing Base Properties, any taxes,
assessments, governmental charges and claims for labor, materials and supplies
for which payment thereof is not being contested and required to be made in
accordance with the provisions of (S)8.9 and has not been timely made and, with
respect to any individual Borrowing Base Property, is in an amount not in excess
of the lesser of (i) $500,000 and (ii) three percent (3%) of the fair market
value of the applicable Borrowing Base Property; or (d) sell, assign, pledge or
otherwise transfer for security any accounts, contract rights, general
intangibles, chattel paper or instruments, with or without recourse, relating to
the Borrowing Base Properties (the foregoing items (a) through (d) being
sometimes referred to in this (S)9.2 collectively as "Liens"), provided that the
                                                               --------
Borrower, the Guarantors and any Wholly-owned Subsidiary may create or incur or
suffer to be created or incurred or to exist:

                     (i)       Liens securing taxes, assessments, governmental
charges or levies or claims for labor, material and supplies, the Indebtedness
with respect to which is not prohibited by (S)9.1(c) or (S)9.2(c) above;

                     (ii)      Liens arising out of deposits or pledges made in
connection with, or to secure payment of, worker's compensation, unemployment
insurance, old age pensions or other social security obligations; and deposits
with utility companies and other similar deposits made in the ordinary course of
business;

                     (iii)     Liens (other than affecting the Borrowing Base
Properties) in respect of judgments or awards, the Indebtedness with respect to
which is not prohibited by (S)9.1(d);

                     (iv)      encumbrances on properties consisting of
easements, rights of way, covenants, zoning and other land-use restrictions,
building restrictions, restrictions on the use of real property and defects and
irregularities in the title thereto; landlord's or lessor's Liens under Leases
to which the Borrower, any Guarantor, or any wholly-owned Subsidiary is a party
or bound; purchase options granted at a price not less than the market value of
such property; and other minor Liens or encumbrances on properties, none of
which interferes materially and adversely with the use of the property affected
in the ordinary conduct of the business of the Borrower, and which matters (x)
do not individually or in the aggregate have a material adverse effect on the
business of BPLP, the Guarantor or, taken as a whole, the BP Group (y) do not
make title to such property unmarketable by the conveyancing standards in effect
where such property is located;

                                      -59-
<PAGE>
 
                     (v)       any Leases;

                     (vi)      Liens and other encumbrances or rights of others
which exist on the date of this Agreement and which do not otherwise constitute
a breach of this Agreement, including, without limitation, Liens created by or
pursuant to the Organizational Documents of the Borrower with respect to a
restriction on sale or refinancing of a Real Estate Asset that would be an
acceptable Lien under the definition of "Unencumbered Asset", so long as all
such Liens, individually, or in the aggregate, do not have a material adverse
effect on BPLP, the Guarantor or, taken as a whole, the BP Group; provided that
                                                                  --------
nothing in this clause (vi) shall be deemed or construed to permit an Borrowing
Base Property to be subject to a Lien to secure Indebtedness;

                     (vii)     as to Real Estate Assets which are acquired after
the date of this Agreement, Liens and other encumbrances or rights of others
which exist on the date of acquisition and which do not otherwise constitute a
breach of this Agreement; provided that nothing in this clause (vii) shall be
deemed or construed to permit a Borrowing Base Property to be subject to a Lien
to secure Indebtedness;

                     (viii)    Liens affecting the Borrowing Base Properties in
respect of judgments or awards that are under appeal or have been in force for
less than the applicable period for taking an appeal, so long as execution is
not levied thereunder or in respect of which, at the time, a good faith appeal
or proceeding for review is being diligently prosecuted, and in respect of which
a stay of execution shall have been obtained pending such appeal or review;
provided that the Borrower shall have obtained a bond or insurance or made other
- --------
arrangements with respect thereto, in each case reasonably satisfactory to the
Agent;

                     (ix)      Liens securing Indebtedness for the purchase
price of capital assets (other than Real Estate Assets but including
Indebtedness in respect of Capitalized Leases for equipment and other equipment
leases) to the extent not otherwise prohibited by (S)9.1; and

                     (x)       other Liens (other than affecting the Borrowing
Base Properties) in connection with any Indebtedness permitted under (S)9.1.

                     Nothing contained in this (S)9.2 shall restrict or limit
the Borrower, the Guarantor or any of their respective Wholly-owned Subsidiaries
from creating a Lien in connection with any Real Estate Asset which is not a
Borrowing Base Property and otherwise in compliance with the other terms of this
Agreement.

           (S)9.3.   Restrictions on Investments. None of the Borrower, the
                     ---------------------------
Guarantor, or any of their respective Subsidiaries will make or permit to exist
or to remain outstanding any Investment except Investments in:

                                      -60-
<PAGE>
 
                     (a)       marketable direct or guaranteed obligations of
the United States of America that mature within two (2) years from the date of
purchase (including investments in securities guaranteed by the United States of
America such as securities in so-called "overseas private investment
corporations");

                     (b)       demand deposits, certificates of deposit, bankers
acceptances and time deposits of United States banks having total assets in
excess of $1,000,000,000;

                     (c)       securities commonly known as "commercial paper"
issued by a corporation organized and existing under the laws of the United
States of America or any state thereof that at the time of purchase have been
rated and the ratings for which are not less than "P 1" if rated by Moody's, and
not less than "A 1" if rated by S&P;

                     (d)       Investments existing on the Closing Date and
listed in the SEC Filings or in the financial statements referred to in (S)7.4
hereof;

                     (e)       other Investments hereafter in connection with
the acquisition and development of Permitted Properties by the Borrower or any
Wholly-owned Subsidiary of the Borrower, provided that the aggregate amounts
                                         --------
actually invested by Borrower (or if not invested directly by Borrower, actually
invested by an Affiliate of the Borrower for which the Borrower has any funding
obligation), the Guarantor and such Wholly-owned Subsidiary at any time in Real
Estate Assets Under Development will not exceed twenty-five percent (25%) of the
Fair Market Value of Assets at the time of any such Investment;

                     (f)       so long as no Event of Default has occurred and
is continuing or would occur after giving effect thereto, Investments (i) in
Real Estate Assets, (ii) in interests in Partially-Owned Real Estate Holding
Entities, (iii) in the stock of or other beneficial interests in Persons whose
primary operations consist of the ownership, development, operation or
management of Real Estate Assets or the ownership of Mortgages, or (iv)
consisting of the acquisition of (A) contracts for the management of real estate
assets for third parties unrelated to the Borrower, or (B) Mortgages, provided
that the aggregate fair market value of Borrower's, Guarantor's, and any such
Subsidiary's interest in such other businesses (excluding management and
development businesses except to the extent of amounts actually invested by the
Borrower, the Guarantor or any such Subsidiary therein) does not exceed twenty-
five percent (25%) of the Consolidated Total Adjusted Asset Value at the time of
any such Investment;

                     (g)       any Investments now or hereafter made in the
Operating Subsidiaries or any Wholly-owned Subsidiary;

                     (h)       Investments in respect of (1) equipment,
inventory and other tangible personal property acquired in the ordinary course
of business, (2) current trade and customer accounts receivable for services
rendered in the ordinary course of business and payable in accordance with
customary trade terms, (3) advances in the ordinary course of business to
employees for travel expenses, drawing accounts and similar expenditures, (4)
prepaid expenses made in the ordinary course of business; and

                                      -61-
<PAGE>
 
                     (i)       shares of so-called "money market funds"
registered with the SEC under the Investment Company Act of 1940 which maintain
a level per-share value, invest principally in marketable direct or guaranteed
obligations of the United States of America and agencies and instrumentalities
thereof, and have total assets in excess of $50,000,000.

           (S)9.4.    Merger, Consolidation and Disposition of Assets.
                      -----------------------------------------------

           None of the Borrower, the Guarantor or any of their respective
Subsidiaries will:

                     (a)       become a party to any merger or consolidation
without prior written approval of the Majority Banks, except that so long as no
Default or Event of Default has occurred and is continuing, or would occur after
giving effect thereto, the merger or consolidation of one or more Persons with
and into the Borrower or the Guarantor shall be permitted in connection with the
acquisition of Real Estate Assets if the Borrower or the Guarantor, as the case
may be, is the surviving entity; provided that prior to any such merger or
                                 --------
consolidation (other than (x) the merger or consolidation of one or more Wholly-
owned Subsidiaries with and into the Borrower or (y) the merger or consolidation
of two or more Wholly owned Subsidiaries of the Borrower, the Borrower shall
provide to the Agent (with copies to the Agent for each Bank) a statement in the
form of Exhibit D hereto signed by the chief financial officer or treasurer of
        ---------
the Borrower and setting forth in reasonable detail computations evidencing
compliance with the covenants contained in (S)(S)10.1 through 10.7 hereof and
certifying, to the best knowledge of the signatory, that no Default or Event of
Default has occurred and is continuing, or would occur and be continuing after
giving effect to such merger or consolidation and all liabilities, fixed or
contingent, pursuant thereto;

                               (b)       without limitation of the other
           provisions of this Agreement, and in particular, subject to the
           provisions of (S)14 hereof relating to the removal of a Real Estate
           Asset from the Borrowing Base in connection with the curing of any
           Default, Event of Default or Non-Material Breach, sell, transfer or
           otherwise dispose of any Real Estate Assets in any single transaction
           having a sales price (net of any Indebtedness secured by a Lien on
           such Real Estate Assets, if any), in excess of $50,000,000
           (collectively and individually, "Sell" or a "Sale") or grant a Lien
           to secure Indebtedness (an "Indebtedness Lien") in any single
           transaction in an amount in excess of $50,000,000 unless, in each
           such event, the Borrower has provided to the Agent (with copies to
           the Agent for each Bank) a compliance certificate in the form of
           Exhibit C-4 or Exhibit C-6, as applicable, hereto signed by the chief
           -----------    -----------
           financial officer, treasurer or controller of the Borrower, setting
           forth in reasonable detail computations evidencing compliance with
           the covenants contained in (S)10 hereof and certifying that no
           Default or Event of Default would exist or occur and be continuing
           after giving effect to all such proposed Sales or Indebtedness Liens.

                                      -62-
<PAGE>
 
           (S)9.5.  Compliance with Environmental Laws. None of the Borrower,
                    ----------------------------------
the Guarantor or any Subsidiary will do any of the following: (a) use any of the
Real Estate Assets or any portion thereof as a facility for the handling,
processing, storage or disposal of Hazardous Substances except for quantities of
Hazardous Substances used in the ordinary course of business and in compliance
with all applicable Environmental Laws, (b) cause or permit to be located on any
of the Real Estate Assets any underground tank or other underground storage
receptacle for Hazardous Substances except in compliance with Environmental
Laws, (c) generate any Hazardous Substances on any of the Real Estate Assets
except in compliance with Environmental Laws, or (d) conduct any activity at any
Real Estate Asset or use any Real Estate Asset in any manner so as to cause a
Release in violation of applicable Environmental Laws; unless, with respect to
clause (d) above, any such occurrence would constitute a Non-Material Breach
hereunder.

           (S)9.6.  Distributions.
                    -------------

                   (a)       The Borrower will not make (i) annual Distributions
in excess of 90% of "funds from operations"; (ii) Distributions in excess of
100% of "funds from operations" for more than three consecutive fiscal quarters;
or (iii) any Distributions during any period after any monetary Event of Default
has occurred; provided, however, (a) that the Borrower may at all times
              --------  -------
(including while a monetary Event of Default is continuing) make Distributions
to the extent (after taking into account all available funds of the Guarantor
from all other sources) required in order to enable the Guarantor to continue to
qualify as a REIT and (b) in the event that the Borrower cures any such monetary
default in clause (iii) above and the Agent has accepted such cure prior to
accelerating the Loan, the limitation of section (iii) above shall cease to
apply with respect to such monetary default.

                   (b)     The Guarantor will not, during any period when any
monetary Event of Default has occurred and is continuing, make any Distributions
in excess of the Distributions required to be made by the Guarantor in order to
maintain its status as a REIT.

           (S)9.7.  Hotel Properties. At any time of determination, the hotel
                    ----------------
properties shall not constitute more than 25% of the Consolidated Total Adjusted
Asset Value or more than 25% of the number of Real Estate Assets. The Agent
acknowledges that, on the Closing Date, there are seventy-four (74) Real Estate
Assets.

           (S)10.   FINANCIAL COVENANTS; COVENANTS REGARDING BORROWING BASE
                    -------------------------------------------------------
PROPERTIES. The Borrower covenants and agrees that, so long as any Loan, Letter
- ----------
of Credit or Revolving Credit Note is outstanding or any Bank has any obligation
to make any Loan or any Bank has any obligation to issue, extend or renew any
Letters of Credit:

           (S)10.1. Consolidated Total Indebtedness. As at the end of any fiscal
                    --------------------------------
quarter, Consolidated Total Indebtedness on the last day of such quarter shall
not exceed 55% of Consolidated Total Adjusted Asset Value for such quarter.

                                      -63-
<PAGE>
 
           (S)10.2. Secured Consolidated Total Indebtedness. As at the end of
                    ---------------------------------------
any fiscal quarter, Secured Consolidated Total Indebtedness shall not exceed (i)
45% of Consolidated Total Adjusted Asset Value for such quarter with respect to
any quarter ending on or before June 30, 1998, and (ii) 40% of Consolidated
Total Adjusted Asset Value for such quarter with respect to any quarter ending
on or after September 30, 1998.

           (S)10.3. Debt Service Coverage. As at the end of any fiscal quarter,
                    ---------------------
the ratio of (i) Consolidated EBITDA for such quarter to (ii) Consolidated Fixed
Charges for such quarter shall not be less than 1.75 to 1.0.

           (S)10.4. Unsecured Consolidated Total Indebtedness. As at the end of
                    -----------------------------------------
any fiscal quarter, the Value of Unencumbered Assets for such quarter shall not
be less than 1.75 times the Unsecured Consolidated Total Indebtedness on the
last day of such quarter.

           (S)10.5. Net Worth. As at the end of any fiscal quarter or any other
                    ---------
date of measurement, the Consolidated Net Worth of the Guarantor and its
Subsidiaries shall not be less than the sum of (i) $125,000,000 plus (ii) 75% of
                                                                ----
the aggregate proceeds received by the Guarantor (net of fees and expenses
customarily incurred in transactions of such type) in connection with any
offering of stock in the Guarantor, plus (iii) 75% of the aggregate value of
                                    ----
operating units issued by the Borrower in connection with asset or stock
acquisitions (valued at the time of issuance by reference to the terms of the
agreement pursuant to which such units are issued), in each case after the
Closing Date and on or prior to the date such determination of Consolidated Net
Worth is made.

           (S)10.6. Borrowing Base Properties.
                    -------------------------

                    (a)       As at the end of any fiscal quarter or any other
date of measurement, the Borrower shall not permit Unsecured Consolidated Total
Indebtedness (exclusive of Accounts Payable, but including amounts outstanding
under any Loans and Letters of Credit after giving effect to Loan Requests) to
exceed 60% of the aggregate Borrowing Base Value.

                    (b)       Except for the Exception Property and the
Grandfathered Properties, not more than 15% of the Borrowing Base Value shall be
derived from any single Borrowing Base Property. One Borrowing Base Property
(the "Exception Property") (but not more than one property (other than the
Grandfathered Properties)), which property can differ from time to time, as
designated by Borrower) can constitute up to 20% of the Borrowing Base Value. In
addition, the Borrowing Base Value derived from the Grandfathered Properties
will not be limited in amount, provided that the percentage of the Borrowing
                               --------
Base Value attributable to the two Grandfathered Properties shall not, in the
aggregate, exceed 50% at any time.

                    (c)       For purposes of determining the Borrowing Base
Value for this (S)10.6, the Net Operating Income of any Borrowing Base Property
acquired during such prior fiscal quarter shall be adjusted on a pro-forma basis
by projecting the Net Operating 

                                      -64-
<PAGE>
 
Income generated by each such acquired Borrowing Base Property for the portion
of the quarter during which it was owned or ground-leased by the Borrower over
the entire quarter.

                    (d)       Notwithstanding the Borrowing Base Conditions, in
the event that the Borrower desires to include any Unencumbered Asset in the
Borrowing Base that does not meet one or more of the Borrowing Base Conditions,
any such Unencumbered Asset shall only be permitted to be included in the
Borrowing Base in the event that (i) the Borrower has submitted to the Agent a
compliance certificate in the form of Exhibit C-5, modified to reflect the non-
                                      -----------
conformity of the proposed Borrowing Base Property, and (ii) the Majority Banks
have provided the Borrower with written approval, in their sole discretion, for
such non-conforming Unencumbered Asset to be included in the Borrowing Base.
Upon any such written approval by the Majority Banks, such Unencumbered Asset
shall be considered a Borrowing Base Property for all purposes hereunder,
provided that on the date of inclusion of any such Unencumbered Asset in the
Borrowing Base (and thereafter in accordance with the terms of this Agreement),
such Unencumbered Asset is otherwise in compliance with the Borrowing Base
Conditions other than with respect to the non-conformity as certified by the
Borrower and approved by the Majority Banks in the compliance certificate
submitted by the Borrower under clause (i) of the preceding sentence, and
provided, further that there is otherwise no Default or Event of Default
- --------  -------
existing upon the date of, or arising as a result of, the inclusion of such
Unencumbered Asset in the Borrowing Base.

           (S)10.7. Borrowing Base Debt Service Coverage Ratio. As of the end of
                    ------------------------------------------
any fiscal quarter or any other date of measurement, the Borrowing Base Debt
Service Coverage Ratio shall not be less than 1.40 to 1.0.

           (S)11.   ESCROW CLOSING. In order to facilitate the Initial Public
                    --------------
Offering, the parties hereto are, on or before June 16, 1997, executing and
delivering into escrow, in accordance with the terms of the Escrow Agreement,
all of the Loan Documents, and certain of the other documents and certificates
referenced in (S)12 as conditions to making the initial Revolving Credit Loans
(the "Escrow Closing"). None of such Loan Documents or other documents or
certificates shall be deemed to have been delivered by the Borrower or any other
party thereto until all of the conditions to release from escrow, as set forth
in the Escrow Agreement, have been satisfied. In the event the conditions for
release of the Loan Documents and other documents and certificates have not been
satisfied on or prior to the Initial Closing Date (as hereinafter defined) or if
extended in accordance with the terms hereof, the Outside Closing Date (as
hereinafter defined), the Banks and the Agent shall have no further obligations
to the Borrower or the Guarantor with respect to the Commitments, the Loans or
any of the other transactions referenced herein and the Borrower and the
Guarantor shall have no further obligations or liabilities to the Banks or the
Agent, except only that the Borrower shall immediately pay to the Agent all
amounts incurred by the Agent and the Banks required to be paid by the Borrower
under (S)17. The "Initial Closing Date" shall be on or before June 20, 1997
unless the Borrower extends the Initial Closing Date to a date not later than
October 2, 

                                      -65-
<PAGE>
 
1997 (the "Outside Closing Date") upon written notice delivered to the Agent by
no later than the third business day preceding the Initial Closing Date.

           (S)12.   CONDITIONS TO THE FIRST ADVANCE. The obligations of the
                    -------------------------------
Banks to make the initial Revolving Credit Loans and of the Fronting Bank to
issue any initial Letters of Credit shall be subject to the satisfaction of the
following conditions precedent on or prior to the Initial Closing Date or, if
properly extended, by Borrower, the Outside Closing Date:

           (S)12.1. Satisfaction of Escrow Conditions. All conditions to release
                    ---------------------------------
of the Loan Documents from Escrow as contained in the Escrow Agreement shall
have been satisfied and pursuant thereto each of the duly executed Loan
Documents shall have been delivered by the respective parties thereto and, shall
be in full force and effect.

           (S)12.2. Loan Documents. Each of the Loan Documents shall have
                    --------------
been duly executed and delivered by the respective parties thereto and shall be
in full force and effect.

           (S)12.3. Certified Copies of Organization Documents. The Agent shall
                    ------------------------------------------
have received (i) from the Borrower a copy, certified as of a recent date by a
duly authorized officer of the Guarantor, in its capacity as general partner of
the Borrower, to be true and complete, of the Agreement of Limited Partnership
of BPLP and any other Organizational Document or other agreement governing the
rights of the partners or other equity owners of the Borrower, and (ii) from the
Guarantor a copy, certified as of a recent date by the appropriate officer of
the State of Delaware to be true and correct, of the corporate charter of the
Guarantor, in each case along with any other organization documents of the
Borrower or the Guarantor and their respective general partners, as the case may
be, and each as in effect on the date of such certification.

           (S)12.4. By-laws; Resolutions. All action on the part of the Borrower
                    --------------------
and the Guarantor necessary for the valid execution, delivery and performance by
the Borrower and the Guarantor of this Agreement and the other Loan Documents to
which any of them is or is to become a party shall have been duly and
effectively taken, and evidence thereof satisfactory to the Banks shall have
been provided to the Agent. The Agent shall have received from the Guarantor
true copies of its by-laws and the resolutions adopted by its board of directors
authorizing the transactions described herein and evidencing the due
authorization, execution and delivery of the Loan Documents to which the
Guarantor and/or the Borrower is a party, each certified by the secretary as of
a recent date to be true and complete.

           (S)12.5. Incumbency Certificate: Authorized Signers. The Agent shall
                    ------------------------------------------
have received from the Guarantor an incumbency certificate, dated as of the
Closing Date, signed by a duly authorized officer of the Guarantor and giving
the name of each individual who shall be authorized: (a) to sign, in the name
and on behalf of the Borrower and the Guarantor, as the case may be, each of the
Loan Documents to which the Borrower or the Guarantor is or is to become a
party; (b) to make Loan and Conversion 

                                      -66-
<PAGE>
 
Requests on behalf of the Borrower and (c) to give notices and to take other
action on behalf of the Borrower or the Guarantor as applicable, under the Loan
Documents.

           (S)12.6.  Title Policies. The Agent (on behalf of the Banks) shall
                     --------------
have received copies of the owner's title policies, if any, for all Borrowing
Base Properties for which the Agent has requested copies, and shall have been
permitted to review such other title policies at BPLP as it has requested prior
to the Closing Date.

           (S)12.7.  Certificates of Insurance. The Agent shall have received,
                     -------------------------
to the extent available (and if not available on the Closing Date, within thirty
(30) days after the Closing Date) (a) current certificates of insurance as to
all of the insurance maintained by Borrower on the Borrowing Base Properties
(including flood insurance if necessary) from the insurer or an independent
insurance broker, identifying insurers, types of insurance, insurance limits,
and policy terms; and (b) such further information and certificates from
Borrower, its insurers and insurance brokers as the Agent may reasonably
request.

           (S)12.8.  Hazardous Substance Assessments. The Agent shall have
                     -------------------------------
received hazardous waste site assessment reports running in favor of the Agent
and the Banks concerning Hazardous Substances (or the threat thereof) and
asbestos with respect to the Borrowing Base Properties, dated no earlier than
July 31, 1996, from environmental engineers reasonably acceptable to the Agent,
such reports to be in form and substance satisfactory to the Agent and each of
the Banks.

           (S)12.9.  Opinion of Counsel Concerning Organization and Loan
                     ---------------------------------------------------
Documents. Each of the Banks and the Agent shall have received favorable
- ---------
opinions addressed to the Banks and the Agent in form and substance reasonably
satisfactory to the Banks and the Agent from Goodwin, Procter and Hoar LLP and
Shaw, Pittman, Potts & Trowbridge, as counsel to the Borrower, the Guarantor and
their respective Subsidiaries, with respect to applicable law, including,
without limitation, Massachusetts law and certain matters of Delaware law.

           (S)12.10. Tax and Securities Law Compliance. Each of the Banks and
                     ----------------------------------
the Agent shall also have received from Goodwin, Procter & Hoar LLP, as counsel
to the Borrower and the Guarantor, a reliance letter addressed to the Banks and
the Agent, in form and substance satisfactory to each of the Banks and the
Agent, together with a favorable opinion with respect to the qualification of
the Guarantor as a REIT and certain other tax matters.

           (S)12.11  Guaranty.  The Guaranty shall have been duly executed and
                     --------
delivered by the Guarantor.

           (S)12.12. Structural Condition Assurances. The Agent and each of the
                     -------------------------------
Banks shall have received evidence satisfactory to the Agent and each of the
Banks as to the good physical condition of the Buildings and that utilities and
public water and sewer service is 

                                      -67-
<PAGE>
 
available at the lot lines of the Borrowing Base Properties and connected
directly to the Buildings on the Borrowing Base Properties with all necessary
Permits.

           (S)12.13. Financial Analysis of Borrowing Base Properties. Each of
                     -----------------------------------------------
the Banks shall have completed, to its satisfaction, a financial analysis of
each Borrowing Base Property, which analysis shall include, without limitation,
a review, with respect to each Borrowing Base Property, of (i) the most recent
rent rolls, (ii) three (3) year historical and projected operating statements,
(iii) cash flow projections, (iv) market data, (v) selected Leases, and (vi)
tenant financial statements, to the extent available. The costs and expenses
incurred by each Bank (other than the Agent) in conducting such analysis shall
be borne by such Bank; provided that the Borrower will furnish such materials to
                       --------
the Banks at the Borrower's expense. The Borrower agrees that at the request of
any Bank it will furnish the materials described in this (S)12.13 to such Bank
after the Closing Date.

           (S)12.14. Inspection of Borrowing Base Properties. The Agent shall
                     ---------------------------------------
have completed to its satisfaction, and at the Borrower's expense, an inspection
of the Borrowing Base Properties which the Agent has not inspected in the one
(1) year period prior to the Closing Date.

           (S)12.15. Certifications from Government Officials; UCC-11 Reports.
                     --------------------------------------------------------
The Agent shall have received long-form certifications from government officials
evidencing the legal existence, good standing and foreign qualification of the
Borrower and the Guarantor, along with a certified copy of the certificate of
limited partnership of the Borrower, all as of the most recent practicable date.

           (S)12.16. Completion of Initial Public Offering; IPO Proceeds. The
                     ---------------------------------------------------
Guarantor (i) shall have successfully completed the Initial Public Offering and
shall have received net IPO Proceeds of at least $600,000,000 or such greater
amount as may be necessary to enable the Borrower to be in compliance with the
terms hereof on the Closing Date; and (ii) all Formation Transactions (as
described in the Prospectus) shall have been completed.

           (S)12.17. Proceedings and Documents. All proceedings in connection
                     -------------------------
with the transactions contemplated by this Agreement, the other Loan Documents
and all other documents incident thereto shall be satisfactory in form and
substance to each of the Banks and to the Agent's counsel, and the Agent, each
of the Banks and such counsel shall have received all information and such
counterpart originals or certified or other copies of such documents as the
Agent may reasonably request.

           (S)12.18. Fees.  The Borrower shall have paid to the Agent, for the
                     ----
accounts of the Banks or for its own account, as applicable, all of the fees and
expenses that are due and payable as of the Closing Date in accordance with this
Agreement.

           (S)12.19. Closing Certificate; Compliance Certificate. The Borrower
                     -------------------------------------------
shall have delivered a Closing Certificate to the Agent, the form of which is
attached hereto as 

                                      -68-
<PAGE>
 
Exhibit E. The Borrower shall have delivered a compliance certificate in the
- ---------
form of Exhibit C-6 hereto evidencing compliance with the covenants set forth in
        -----------
(S)10 hereof on a pro forma basis.

           (S)12.20. Partnership Documents. The Agent shall have received from
                     ---------------------
the Borrower true copies of all Partnership Documents.

           (S)12.21. Release Documents. The Agent shall have delivered to the
                     -----------------
Borrower appropriate release documentation necessary to release all security
interests granted by the Borrower in the Borrowing Base Properties, including,
without limitation, appropriate releases of mortgages and deeds of trust and UCC
termination statements.

           (S)13.    CONDITIONS TO ALL BORROWINGS. The obligations of the Banks
                     ----------------------------
to make any Loan and of any Bank to issue, extend or renew any Letter of Credit,
in each case, whether on or after the Closing Date, shall also be subject to the
satisfaction of the following conditions precedent:

           (S)13.1.  Representations True; No Event of Default; Compliance
                     -----------------------------------------------------
Certificate. Each of the representations and warranties made by or on behalf of
- -----------
the Borrower, the Guarantor or any of their respective Subsidiaries contained in
this Agreement, the other Loan Documents or in any document or instrument
delivered pursuant to or in connection with this Agreement shall be true as of
the date as of which they were made and shall also be true at and as of the time
of the making of each Loan or the issuance, extension or renewal of each Letter
of Credit, with the same effect as if made at and as of that time (except (i) to
the extent of changes resulting from transactions contemplated or not prohibited
by this Agreement or the other Loan Documents (including, without limitation,
the fact that a Real Estate Asset may cease to be a Borrowing Base Property
pursuant to the terms of this Agreement) and changes occurring in the ordinary
course of business, (ii) to the extent that such representations and warranties
relate expressly to an earlier date and (iii) to the extent otherwise
represented by the Borrower with respect to the representation set forth in
(S)7.10); and no Default or Event of Default under this Agreement shall have
occurred and be continuing on the date of any Loan Request or on the Drawdown
Date of any Loan. Each of the Banks shall have received a certificate of the
Borrower signed by an authorized officer of the Borrower as provided in
(S)2.4(iv)(c).

           (S)13.2.  No Legal Impediment. No change shall have occurred any law
                     -------------------
or regulations thereunder or interpretations thereof that in the reasonable
opinion, as determined in good faith, of the Agent or any Bank would make it
illegal for any Bank to make such Loan or to participate in the issuance,
extension or renewal of such Letter of Credit or, in the reasonable opinion, as
determined in good faith, of the Agent, would make it illegal to issue, extend
or renew such Loan or Letter of Credit.

           (S)13.3.  Governmental Regulation. Each Bank shall have received such
                     -----------------------
statements in substance and form reasonably satisfactory to such Bank as such
Bank shall reasonably require in good faith for the purpose of compliance with
any applicable regulations of the Comptroller of the Currency or the Board of
Governors of the Federal Reserve System.

                                      -69-
<PAGE>
 
           (S)14.    EVENTS OF DEFAULT; ACCELERATION: ETC.
                     ------------------------------------

           (S)14.1.  Events of Default and Acceleration. If any of the following
                     ----------------------------------
events ("Events of Default") shall occur:

                     (a)       the Borrower shall fail to pay any principal of
the Loans when the same shall become due and payable;

                     (b)       the Borrower shall fail to pay any interest on
the Loans or any other sums due hereunder or under any of the other Loan
Documents (including, without limitation, amounts due under (S)8.17) when the
same shall become due and payable, and such failure continues for three (3) days
(provided that in the case of such sums due other than for interest, the
 --------
Borrower shall have received from the Agent notice of the nature and amount of
such other amounts and that payment therefor is due);

                     (c)       the Borrower, the Guarantor or any of their
respective Subsidiaries shall fail to comply with any of their respective
covenants contained in the following:

                                         (i)    (S)8.1 (except with respect to
                               principal, interest and other sums covered by
                               clauses (a) or (b) above);

                                        (ii)    (S).8.5 (clauses (a) through
                               (d)), unless such failure is cured within fifteen
                               (15) Business Days;

                                       (iii)    (S)8.6 (as to the legal
                               existence of Borrower), unless such breach
                               relates to a Borrower other than BPLP and is a
                               Non-Material Breach;

                                        (iv)    (S)8.7 (as to the legal
                               existence and REIT status of the Guarantor);

                                         (v)    (S)8.10, unless such failure is
                               cured within three (3) Business Days;

                                        (vi)    (S)8.12;

                                       (vii)    (S).8.13, unless, with respect
                               solely to clauses (ii) and (iii) of (S)8.13, such
                               failure is cured within thirty (30) days;

                                      (viii)    (S)8.14, unless, with respect
                               solely to the last sentence of clause (a) of
                               (S)8.14, such failure is cured within thirty (30)
                               days;

                                       (ix)     (S)8.16;

                                      -70-
<PAGE>
 
                                          (x)      (S)9.1;

                                          (xi)     (S)9.2 (pertaining to liens,
                               mortgages, pledges, attachments or other security
                               interests with respect to Borrowing Base
                               Properties) unless (1) with respect solely to
                               such liens or attachments which are not
                               affirmatively created or incurred, such failure
                               is cured within thirty (30) days (with no
                               double-counting of any cure period set forth in
                               (S)9.2) or (2) such failure is a breach which is
                               a Non-Material Breach;

                                          (xii)    (S)9.3;

                                          (xiii)   (S)9.4;

                                          (xiv)    (S)9.6;

                                          (xv)     (S)9.7; and

                                          (xvi)    (S)10;

                     (d)       the Borrower, the Guarantor or any of their
respective Subsidiaries shall fail to perform any other term, covenant or
agreement contained herein or in any of the other Loan Documents (other than
those specified elsewhere in this (S)14) and such failure continues for thirty
(30) days after written notice of such failure from the Agent (such notice not,
however, being required for any failure with respect to which the Borrower is
otherwise obligated hereunder to notify the Agent or the Banks), provided,
                                                                 --------
however, that if the Borrower is diligently and in good faith prosecuting a cure
- -------
of any such failure or breach that is capable of being cured (all as determined
by the Agent in its reasonable and good faith judgment), the Borrower shall be
permitted an additional thirty (30) days (but in no event more than an aggregate
of sixty (60) days after any such initial written notice from the Agent) to
effect such cure;

                     (e)        any representation or warranty of the Borrower,
the Guarantor or any of their respective Subsidiaries in this Agreement or any
of the other Loan Documents shall prove to have been false in any material
respect upon the date when made or deemed to have been made or repeated and the
same is not otherwise specified herein to be a Non-Material Breach;

                     (f)       the Borrower, the Guarantor or any of their
respective Subsidiaries or, to the extent of Recourse to the Borrower, the
Guarantor or such Subsidiaries thereunder, any of their respective Affiliates,
shall fail to pay at maturity, or within any applicable period of grace, any
obligation for borrowed money or credit received or in respect of any
Capitalized Leases (other than non-recourse obligations or credit), which is in
excess of $50,000,000, either individually or in the aggregate, or fail to
observe or perform any material term, covenant, condition or agreement contained
in any agreement, document or instrument by which it is bound evidencing,
securing or otherwise relating 

                                      -71-
<PAGE>
 
to such Recourse obligations, evidencing or securing borrowed money or credit
received or in respect of any Capitalized Leases for such period of time (after
the giving of appropriate notice if required) as would permit the holder or
holders thereof or of any obligations issued thereunder in excess of
$50,000,000, either individually or in the aggregate, to accelerate the maturity
thereof; provided, however that notwithstanding the foregoing, no Event of
         --------  -------
Default under the Loan Document shall occur pursuant to this subparagraph (f)
unless and until the holder or holders of such recourse indebtedness have
declared an event of default beyond any applicable notice and grace periods, if
any, on in excess of $50,000,000 of such recourse indebtedness either
individually or in the aggregate;

                     (g)       any of BPLP, the Guarantor or any of their
respective Subsidiaries shall make an assignment for the benefit of creditors,
or admit in writing its inability to pay or generally fail to pay its debts as
they mature or become due, or shall petition or apply for the appointment of a
trustee or other custodian, liquidator or receiver of any of BPLP, the Guarantor
or any of their respective Subsidiaries or of any substantial part of the
properties or assets of any of such parties or shall commence any case or other
proceeding relating to any of the BPLP, the Guarantor or any of their respective
Subsidiaries under any bankruptcy, reorganization, arrangement, insolvency,
readjustment of debt, dissolution or liquidation or similar law of any
jurisdiction, now or hereafter in effect, or shall take any action to authorize
or in furtherance of any of the foregoing, or if any such petition or
application shall be filed or any such case or other proceeding shall be
commenced against any of BPLP, the Guarantor or any of their respective
Subsidiaries and (i) any of BPLP, the Guarantor or any of their respective
Subsidiaries shall indicate its approval thereof, consent thereto or
acquiescence therein or (ii) any such petition, application, case or other
proceeding shall continue undismissed, or unstayed and in effect, for a period
of ninety (90) days, except, with respect solely to such parties other than BPLP
and the Guarantor, any of the foregoing constitutes a Non-Material Breach;

                     (h)       a decree or order is entered appointing any
trustee, custodian, liquidator or receiver or adjudicating any of BPLP, the
Guarantor or any of their respective Subsidiaries bankrupt or insolvent, or
approving a petition in any such case or other proceeding, or a decree or order
for relief is entered in respect of any of BPLP, the Guarantor or any of their
respective Subsidiaries in an involuntary case under federal bankruptcy laws as
now or hereafter constituted, except, with respect solely to such parties other
than BPLP and the Guarantor, any of the foregoing constitutes a Non-Material
Breach;

                     (i)       there shall remain in force, undischarged,
unsatisfied and unstayed, for more than thirty (30) days, whether or not
consecutive, any uninsured final judgment against any of BPLP, the Guarantor or
any of their respective Subsidiaries that, with other outstanding uninsured
final judgments, undischarged, unsatisfied and unstayed, against any of such
parties exceeds in the aggregate $10,000,000, except, with respect solely to
such parties other than BPLP and the Guarantor, any of the foregoing constitutes
a Non-Material Breach;

                                      -72-
<PAGE>
 
                     (j)       any of the Loan Documents or any material
provision of any Loan Document shall be canceled, terminated, revoked or
rescinded otherwise than in accordance with the terms thereof or with the
express prior written agreement, consent or approval of the Agent or the
Guaranty shall be canceled, terminated, revoked or rescinded at any time or for
any reason whatsoever, or any action at law, suit or in equity or other legal
proceeding to make unenforceable, cancel, revoke or rescind any of the Loan
Documents shall be commenced by or on behalf of the Borrower or any of its
Subsidiaries or the Guarantor or any of its Subsidiaries, or any court or any
other governmental or regulatory authority or agency of competent jurisdiction
shall make a determination that, or issue a judgment, order, decree or ruling to
the effect that, any one or more of the Loan Documents is illegal, invalid or
unenforceable as to any material terms thereof;

                     (k)       any "Event of Default" or default (after notice
and expiration of any period of grace, to the extent provided, as defined or
provided in any of the other Loan Documents, shall occur and be continuing;

                     (l)       with respect to any Guaranteed Pension Plan, an
ERISA Reportable Event shall have occurred and the Majority Banks shall have
determined in their reasonable discretion that such event reasonably could be
expected to result in liability of the Borrower or any of its Subsidiaries or
any Guarantor or any of its Subsidiaries to the PBGC or such Guaranteed Pension
Plan in an aggregate amount exceeding $10,000,000 and such event in the
circumstances occurring reasonably could constitute grounds for the termination
of such Guaranteed Pension Plan by the PBGC or for the appointment by the
appropriate United States District Court of a trustee to administer such
Guaranteed Pension Plan; or a trustee shall have been appointed by the United
States District Court to administer such Plan; or the PBGC shall have instituted
proceedings to terminate such Guaranteed Pension Plan;

                     (m)       subject to the Borrower's right to remove Real
Estate Assets from the Borrowing Base in accordance with the provisions set
forth below in this (S)14, the failure of any of the Real Estate Assets being
included from time to time as Borrowing Base Properties to comply with any of
the conditions set forth in the definition of Borrowing Base Properties; or

                     (n)       the Guarantor shall at any time fail to be the
sole general partner of BPLP; 

                     then, and in any such event, so long as the same may be
continuing, the Agent may, and upon the request of the Majority Banks shall, by
notice in writing to the Borrower, declare all amounts owing with respect to
this Agreement, the Revolving Credit Notes and the other Loan Documents and all
Reimbursement Obligations to be, and they shall thereupon forthwith become,
immediately due and payable without presentment, demand, protest or other notice
of any kind, all of which are hereby expressly waived by the Borrower, the
Guarantor and each of their respective 

                                      -73-
<PAGE>
 
Subsidiaries; provided that in the event of any Event of Default specified in
              --------
(S)14.1(g) or 14.1(h), all such amounts shall become immediately due and payable
automatically and without any requirement of notice from any of the Banks or the
Agent or action by the Banks or the Agent.

                     For purposes of this Section 14, the term "Non-Material
Breach" shall refer to a breach of any representation, warranty or covenant
contained in this Agreement to which the term "Non-Material Breach" is expressly
applied herein, but only to the extent such breach does not (A) materially
adversely affect the business, properties or financial condition of BPLP, the
Guarantor or, taken as a whole, the BP Group or (B) adversely affect the ability
of BPLP, the Guarantor or, taken as a whole, the BP Group, to fulfill the
Obligations to the Banks and the Agent (including, without limitation, to repay
all amounts outstanding on the Loans, together with interest and charges thereon
when due).

                     Notwithstanding the foregoing provisions of this (S)14.1
and in addition to the provisions set forth in the immediately preceding
paragraph, in the event of a Default, Event of Default or Non-Material Breach
arising as a result of the inclusion of any Real Estate Asset in the Borrowing
Base at any particular time of reference, if such Default, Event of Default or
Non-Material Breach is capable of being cured by the exclusion of such Real
Estate Asset from the Borrowing Base and from all other covenant calculations
under (S)10 or otherwise, the Borrower shall be permitted a period not to exceed
ten (10) days to submit to the Agent (with copies to the Agent for each Bank) a
compliance certificate in the form of Exhibit C-4 hereto evidencing compliance
with Section 2.1 and with all of the covenants set forth in (S)10 (with
calculations evidencing such compliance after excluding from Borrowing Base Net
Operating Income all of the Net Operating Income generated by the Real Estate
Asset to be excluded from the Borrowing Base) and with the Borrowing Base
Conditions, and otherwise certifying that, after giving effect to the exclusion
of such Real Estate Asset from the Borrowing Base, no Default, Event of Default
or Non-Material Breach will be continuing.

          (S)14.2. Termination of Commitments. If any one or more Events of
                   --------------------------
Default specified in (S)14.1(g) or (S)14.1(h) shall occur, any unused portion of
the Commitments hereunder shall forthwith terminate and the Banks shall be
relieved of all obligations to make Loans to the Borrower and the Agent and any
Fronting Bank shall be relieved of all further obligations to issue, extend or
renew Letters of Credit. If any other Event of Default shall have occurred and
be continuing, whether or not the Banks shall have accelerated the maturity of
the Loans pursuant to (S)14.1, any Bank may, by notice to the Borrower,
terminate the unused portion of that Bank's Commitment hereunder, and upon such
notice being given such unused portion of such Commitment shall terminate
immediately, such Bank shall be relieved of all further obligations to make
Loans, the Agent and any Fronting Bank shall be relieved of all further
obligations to issue, extend or renew Letters of Credit and the Total
Commitments shall be reduced accordingly. No such termination of a Commitment
hereunder shall relieve the Borrower of any of the Obligations or any of its
existing obligations to such Bank arising under other agreements or instruments.

                                      -74-
<PAGE>
 
          (S)14.3. Remedies. In the event that one or more Events of Default
                   --------    
shall have occurred and be continuing, whether or not the Banks shall have
accelerated the maturity of the Loans pursuant to (S)14.1, the Majority Banks
may direct the Agent to proceed to protect and enforce the rights and remedies
of the Agent and the Banks under this Agreement, the Revolving Credit Notes, any
or all of the other Loan Documents or under applicable law by suit in equity,
action at law or other appropriate proceeding (including for the specific
performance of any covenant or agreement contained in this Agreement or the
other Loan Documents or any instrument pursuant to which the Obligations are
evidenced and, to the full extent permitted by applicable law, the obtaining of
the ex parte appointment of a receiver), and, if any amount shall have become
due, by declaration or otherwise, proceed to enforce the payment thereof or any
other legal or equitable right or remedy of the Agent and the Banks under the
Loan Documents or applicable law. No remedy herein conferred upon the Banks or
the Agent or the holder of any Revolving Credit Note or purchaser of any Letter
of Credit Participation is intended to be exclusive of any other remedy and each
and every remedy shall be cumulative and shall be in addition to every other
remedy given hereunder or under any of the other Loan Documents or now or
hereafter existing at law or in equity or by statute or any other provision of
law.

          (S)15.   SETOFF.  Neither the Agent nor any of the Banks shall
                   ------
have any right of set-off or the like with respect to the Obligations against
any assets of the Borrower, the Guarantor, their respective Subsidiaries or any
Partially-Owned Entity.

          (S)16.   THE AGENT.
                   --------- 

          (S)16.1. Authorization. (a) The Agent is authorized to take such
                   -------------
action on behalf of each of the Banks and to exercise all such powers as are
hereunder and under any of the other Loan Documents and any related documents
delegated to the Agent, together with such powers as are reasonably incident
thereto, provided that no duties or responsibilities not expressly assumed
         --------
herein or therein shall be implied to have been assumed by the Agent. The
relationship between the Agent and the Banks is and shall be that of agent and
principal only, and nothing contained in this Agreement or any of the other Loan
Documents shall be construed to constitute the Agent as a trustee or fiduciary
for any Bank.

                     (b)       The Borrower, without further inquiry or
investigation, shall, and is hereby authorized by the Banks to, assume that all
actions taken by the Agent hereunder and in connection with or under the Loan
Documents are duly authorized by the Banks. The Banks shall notify Borrower of
any successor to Agent by a writing signed by Majority Banks, which successor
shall be reasonably acceptable to the Borrower so long as no Default or Event of
Default has occurred and is continuing. The Borrower acknowledges that any Bank
which acquires BankBoston is acceptable as a successor to the Agent.

                                      -75-
<PAGE>
 
          (S)16.2. Employees and Agents. The Agent may exercise its powers and
                   -------------------- 
execute its duties by or through employees or agents and shall be entitled to
take, and to rely on, advice of counsel concerning all matters pertaining to its
rights and duties under this Agreement and the other Loan Documents. The Agent
may utilize the services of such Persons as the Agent in its sole discretion may
reasonably determine, and all reasonable fees and expenses of any such Persons
shall be paid by the Borrower.

          (S)16.3. No Liability. Neither the Agent, nor any of its
                   ------------
shareholders, directors, officers or employees nor any other Person assisting
them in their duties nor any agent or employee thereof, shall be liable for any
waiver, consent or approval given or any action taken, or omitted to be taken,
in good faith by it or them hereunder or under any of the other Loan Documents,
or in connection herewith or therewith, or be responsible for the consequences
of any oversight or error of judgment whatsoever, except that the Agent may be
liable for losses due to its willful misconduct or gross negligence.

          (S)16.4. No Representations. The Agent shall not be responsible for
                   ------------------
the execution or validity or enforceability of this Agreement, the Revolving
Credit Notes, the Letters of Credit, or any of the other Loan Documents or for
the validity, enforceability or collectibility of any such amounts owing with
respect to the Revolving Credit Notes, or for any recitals or statements,
warranties or representations made herein or in any of the other Loan Documents
or in any certificate or instrument hereafter furnished to it by or on behalf of
the Guarantor or the Borrower or any of their respective Subsidiaries, or be
bound to ascertain or inquire as to the performance or observance of any of the
terms, conditions, covenants or agreements in this Agreement or the other Loan
Documents. The Agent shall not be bound to ascertain whether any notice,
consent, waiver or request delivered to it by the Borrower or the Guarantor or
any holder of any of the Revolving Credit Notes shall have been duly authorized
or is true, accurate and complete. The Agent has not made nor does it now make
any representations or warranties, express or implied, nor does it assume any
liability to the Banks, with respect to the credit worthiness or financial
condition of the Borrower or any of its Subsidiaries or the Guarantor or any of
the Subsidiaries or any tenant under a Lease or any other entity. Each Bank
acknowledges that it has, independently and without reliance upon the Agent or
any other Bank, and based upon such information and documents as it has deemed
appropriate, made its own credit analysis and decision to enter into this
Agreement.

          (S)16.5.    Payments.
                      --------

                     (a)       A payment by the Borrower to the Agent hereunder
or any of the other Loan Documents for the account of any Bank shall constitute
a payment to such Bank. The Agent agrees to distribute to each Bank such Bank's
pro rata share of payments received by the Agent for the account of the Banks,
as provided herein or in any of the other Loan Documents. All such payments
shall be made on the date received, if before 1:00 p.m., and if after 1:00 p.m.,
on the next Business Day. If payment is not made on the day received, the funds
shall be invested by the Agent in overnight obligations, and interest thereon
paid pro rata to the Banks.
     --- ---- 

                                      -76-
<PAGE>
 
                     (b)       If in the reasonable opinion of the Agent the
distribution of any amount received by it in such capacity hereunder, under the
Revolving Credit Notes or under any of the other Loan Documents might involve it
in material liability, it may refrain from making distribution until its right
to make distribution shall have been adjudicated by a court of competent
jurisdiction, provided that the Agent shall invest any such undistributed
              --------
amounts in overnight obligations on behalf of the Banks and interest thereon
shall be paid pro rata to the Banks. If a court of competent jurisdiction shall
              --- ----
adjudge that any amount received and distributed by the Agent is to be repaid,
each Person to whom any such distribution shall have been made shall either
repay to the Agent its proportionate share of the amount so adjudged to be
repaid or shall pay over the same in such manner and to such Persons as shall be
determined by such court.

                     (c)       Notwithstanding anything to the contrary
contained in this Agreement or any of the other Loan Documents, any Bank that
fails (i) to make available to the Agent its pro rata share of any Loan or to
purchase any Letter of Credit Participation or (ii) to adjust promptly such
Bank's outstanding principal and its pro rata Commitment Percentage as provided
                                     --- ----  
in (S)2.1, shall be deemed delinquent (a "Delinquent Bank") and shall be deemed
a Delinquent Bank until such time as such delinquency is satisfied. A Delinquent
Bank shall be deemed to have assigned any and all payments due to it from the
Borrower, whether on account of outstanding Loans, interest, fees or otherwise,
to the remaining nondelinquent Banks for application to, and reduction of, their
respective pro rata shares of all outstanding Loans. The Delinquent Bank hereby
           --- ----  
authorizes the Agent to distribute such payments to the nondelinquent Banks in
proportion to their respective pro rata shares of all outstanding Loans. If not
                               --- ---- 
previously satisfied directly by the Delinquent Bank, a Delinquent Bank shall be
deemed to have satisfied in full a delinquency when and if, as a result of
application of the assigned payments to all outstanding Loans of the
nondelinquent Banks, the Banks' respective pro rata shares of all outstanding
                                           --- ----
Loans have returned to those in effect immediately prior to such delinquency and
without giving effect to the nonpayment causing such delinquency.

          (S)16.6. Holders of Revolving Credit Notes. The Agent may deem and
                    ---------------------------------
treat the payee of any Revolving Credit Notes or the purchaser of any Letter of
Credit Participation as the absolute owner or purchaser thereof for all purposes
hereof until it shall have been furnished in writing with a different name by
such payee or by a subsequent holder, assignee or transferee.

          (S)16.7. Indemnity. The Banks ratably and severally agree hereby to
                    ---------    
indemnify and hold harmless the Agent and its Affiliates from and against any
and all claims, actions and suits (whether groundless or otherwise), losses,
damages, costs, expenses (including any expenses for which the Agent has not
been reimbursed by the Borrower as required by (S)17), and liabilities of every
nature and character arising out of or related to this Agreement, the Revolving
Credit Notes, or any of the other Loan Documents or the transactions
contemplated or evidenced hereby or thereby, or the Agent's actions taken
hereunder or thereunder, except to the extent that any of the same shall be
directly caused by the Agent's willful misconduct or gross negligence.

                                      -77-
<PAGE>
 
          (S)16.8. Agent as Bank. In its individual capacity as a Bank,
                    -------------
BankBoston shall have the same obligations and the same rights, powers and
privileges in respect to its Commitment and the Loans made by it, and as the
holder of any of the Revolving Credit Notes and as the purchaser of any Letter
of Credit Participations, as it would have were it not also the Agent.

           (S)16.9. Notification of Defaults and Events of Default. Each Bank
                    ----------------------------------------------    
hereby agrees that, upon learning of the existence of a Default or an Event of
Default, it shall (to the extent notice has not previously been provided)
promptly notify the Agent thereof. The Agent hereby agrees that upon receipt of
any notice under this (S)16.9 it shall promptly notify the other Banks of the
existence of such Default or Event of Default.

           (S)16.10. Duties in the Case of Enforcement. In case one or more
                     ---------------------------------
Events of Default have occurred and shall be continuing, and whether or not
acceleration of the Obligations shall have occurred, the Agent shall, if (a) so
requested by the Majority Banks and (b) the Banks have provided to the Agent
such additional indemnities and assurances against expenses and liabilities as
the Agent may reasonably request, proceed to enforce the provisions of this
Agreement and exercise all or any such other legal and equitable and other
rights or remedies as it may have in respect of enforcement of the Banks' rights
against the Borrower, the Guarantor and their respective Subsidiaries under this
Agreement and the other Loan Documents. The Majority Banks may direct the Agent
in writing as to the method and the extent of any such enforcement, the Banks
(including any Bank which is not one of the Majority Banks) hereby agreeing to
ratably and severally indemnify and hold the Agent harmless from all liabilities
incurred in respect of all actions taken or omitted in accordance with such
directions, provided that the Agent need not comply with any such direction to
the extent that the Agent reasonably believes the Agent's compliance with such
direction to be unlawful or commercially unreasonable in any applicable
jurisdiction.

           (S)16.11. Successor Agent. BankBoston, or any successor Agent, may
                     ---------------
resign as Agent at any time by giving written notice thereof to the Banks and to
the Borrower. The Majority Banks may remove the Agent in the event of the
Agent's willful misconduct or gross negligence or in the event that the Agent
ceases to hold a Commitment under this Agreement. In addition, the Borrower may
remove the Agent in the event that the Agent holds (without participation) less
than the Minimum Commitment, provided that if the Agent holds less than the
                             --------   
Minimum Commitment at any time as a result of the merger or consolidation of any
of the other Banks or as a result of events other than the sale by the Agent of
any portion of its Commitment, the Agent shall have a period of ninety (90) days
after its failure to hold at least the Minimum Commitment to cure such failure.
Any such resignation or removal shall be effective upon appointment and
acceptance of a successor Agent, as hereinafter provided. Upon any such
resignation or removal, the Majority Banks shall have the right to appoint a
successor Agent, which is a Bank under this Agreement and which holds at least
the Minimum Commitment, provided that so long as no Default or Event of Default
                        --------
has occurred and is continuing the Borrower shall have the right to approve any
successor Agent, which approval shall not be unreasonably withheld. If, in the
case of a resignation by the Agent, no successor Agent shall have 

                                      -78-
<PAGE>
 
been so appointed by the Majority Banks and approved by the Borrower, and shall
have accepted such appointment, within thirty (30) days after the retiring
Agent's giving of notice of resignation, then the retiring Agent may, on behalf
of the Banks, appoint any one of the other Banks as a successor Agent. The
Borrower acknowledges that any Bank which acquires BankBoston is acceptable as a
successor Agent. Upon the acceptance of any appointment as Agent hereunder by a
successor Agent, such successor Agent shall thereupon succeed to and become
vested with all the rights, powers, privileges and duties of the retiring or
removed Agent, and the retiring or removed Agent shall be discharged from all
further duties and obligations as Agent under this Agreement. After any Agent's
resignation or removal hereunder as Agent, the provisions of this (S)16 shall
inure to its benefit as to any actions taken or omitted to be taken by it while
it was Agent under this Agreement. The Agent agrees that it shall not assign any
of its rights or duties as Agent to any other Person.

           (S)16.12.  Notices.  Any notices or other information required
                      -------  
hereunder to be provided to the Agent (with copies to the Agent for each Bank)
shall be forwarded by the Agent to each of the Banks on the same day (if
practicable) and, in any case, on the next Business Day following the Agent's
receipt thereof

           (S)17. EXPENSES. The Borrower agrees to pay (a) the reasonable costs
                  --------
of producing and reproducing this Agreement, the other Loan Documents and the
other agreements and instruments mentioned herein, (b) the reasonable fees,
expenses and disbursements of the Agent's outside counsel or any local counsel
to the Agent incurred in connection with the preparation, administration or
interpretation of the Loan Documents and other instruments mentioned herein,
each closing hereunder, and amendments, modifications, approvals, consents or
waivers hereto or hereunder, (c) the fees, expenses and disbursements of the
Agent incurred by the Agent in connection with the preparation, administration
or interpretation of the Loan Documents and other instruments mentioned herein,
including, without limitation, the costs incurred by the Agent in connection
with its inspection of the Borrowing Base Properties (subject to (S)12.14), and,
without double-counting amounts under clause (b) above, the fees and
disbursements of the Agent's counsel in preparing the documentation, (d) the
fees, costs, expenses and disbursements of the Agent and its Affiliates incurred
in connection with the initial syndication and/or participations of the Loans
(whether occurring before or after the closing hereunder), including, without
limitation, reasonable legal fees, travel costs, costs of preparing syndication
materials and photocopying costs, provided that the Borrower shall not incur any
costs or fees of any kind in connection with any participation, sale or other
syndication of any portion of the Loans which occurs after the initial
syndication other than reasonable legal fees and expenses incurred in connection
with any participation, sale or syndication undertaken at the request of the
Borrower or (in addition to any other fees or expenses relating thereto) in
connection with an amendment or increase to the amount of the Total Commitment,
(e) all reasonable expenses (including reasonable attorneys' fees and costs,
which attorneys may be employees of any Bank or the Agent, and the fees and
costs of engineers, investment bankers, or other experts retained by any Bank or
the Agent in connection with any such enforcement proceedings) incurred by any
Bank or the Agent in connection with (i) the 

                                      -79-
<PAGE>
 
enforcement of or preservation of rights under any of the Loan Documents against
the Borrower or any of its Subsidiaries or the Guarantor or the administration
thereof after the occurrence and during the continuance of a Default or Event of
Default (including, without limitation, expenses incurred in any restructuring
and/or "workout" of the Loans), and (ii) any litigation, proceeding or dispute
whether arising hereunder or otherwise, in any way related to any Bank's or the
Agent's relationship with the Borrower or any of its Subsidiaries or the
Guarantor, (f) all reasonable fees, expenses and disbursements of the Agent
incurred in connection with UCC searches, UCC terminations or mortgage
discharges, and (g) all costs incurred by the Agent in the future in connection
with its inspection of the Borrowing Base Properties, provided that prior to the
                                                      --------  
occurrence of an Event of Default, the Borrower shall not be required to pay for
more than one inspection of each Borrowing Base Property per year. The covenants
of this (S)17 shall survive payment or satisfaction of payment of amounts owing
with respect to the Revolving Credit Notes.

           (S)18. INDEMNIFICATION. The Borrower agrees to indemnify and hold
                  ---------------      
harmless the Agent and each of the Banks and the shareholders, directors,
agents, officers, subsidiaries and affiliates of the Agent and each of the Banks
from and against any and all claims, actions and suits, whether groundless or
otherwise, and from and against any and all liabilities, losses, settlement
payments, obligations, damages and expenses of every nature and character in
connection therewith, arising out of this Agreement or any of the other Loan
Documents or the transactions contemplated hereby or thereby or which otherwise
arise in connection with the financing, including, without limitation, (a) any
actual or proposed use by the Borrower or any of its Subsidiaries of the
proceeds of any of the Loans, (b) the Borrower or any of its Subsidiaries or the
Guarantor entering into or performing this Agreement or any of the other Loan
Documents, or (c) pursuant to (S)8.17 hereof, in each case including, without
limitation, the reasonable fees and disbursements of counsel and allocated costs
of internal counsel incurred in connection with any such investigation,
litigation or other proceeding, provided, however, that the Borrower shall not
                                -----------------
be obligated under this (S)18 to indemnify any Person for liabilities arising
from such Person's own gross negligence, willful misconduct or breach of this
Agreement. In litigation, or the preparation therefor, the Borrower shall be
entitled to select counsel reasonably acceptable to the Majority Banks, and the
Agent (as approved by the Majority Banks) shall be entitled to select their own
supervisory counsel, and, in addition to the foregoing indemnity, the Borrower
agrees to pay promptly the reasonable fees and expenses of each such counsel.
Prior to any settlement of any such litigation by the Banks, the Banks shall
provide the Borrower and the Guarantor with notice and an opportunity to address
any of their concerns with the Banks, and the Banks shall not settle any
litigation without first obtaining Borrower's consent thereto, which consent
shall not be unreasonably withheld or delayed. If and to the extent that the
obligations of the Borrower under this (S)18 are unenforceable for any reason,
the Borrower hereby agrees to make the maximum contribution to the payment in
satisfaction of such obligations which is permissible under applicable law. The
provisions of this (S)18 shall survive the repayment of the Loan and the
termination of the obligations of the Banks hereunder and shall continue in full
force and effect as long as the possibility of any such claim, action, cause of
action or suit exists.

                                      -80-
<PAGE>
 
           (S)19.   SURVIVAL OF COVENANTS, ETC. All covenants, agreements,
                    ---------------------------
representations and warranties made herein, in the Revolving Credit Notes, in
any of the other Loan Documents or in any documents or other papers delivered by
or on behalf of the Borrower or any of its Subsidiaries or the Guarantor
pursuant hereto shall be deemed to have been relied upon by the Banks and the
Agent, notwithstanding any investigation heretofore or hereafter made by any of
them, and shall survive the making by the Banks of any of the Loans and the
issuance, extension or renewal of any Letters of Credit, as herein contemplated,
and shall continue in full force and effect so long as any Letter of Credit or
any amount due under this Agreement or the Revolving Credit Notes or any of the
other Loan Documents remains outstanding or any Bank has any obligation to make
any Loans or the Agent or any Fronting Bank has any obligation to issue, extend
or renew any Letter of Credit. The indemnification obligations of the Borrower
provided herein and in the other Loan Documents shall survive the full repayment
of amounts due and the termination of the obligations of the Banks hereunder and
thereunder to the extent provided herein and therein. All statements contained
in any certificate or other paper delivered to any Bank or the Agent at any time
by or on behalf of the Borrower or any of its Subsidiaries or the Guarantor
pursuant hereto or in connection with the transactions contemplated hereby shall
constitute representations and warranties by the Borrower or such Subsidiary or
the Guarantor hereunder.

           (S)20.   ASSIGNMENT; PARTICIPATIONS; ETC.
                    --------------------------------

           (S)20.1. Conditions to Assignment by Banks. Except as provided
                    ----------------------------------
herein, each Bank may assign to one or more Eligible Assignees all or a portion
of its interests, rights and obligations under this Agreement (including all or
a portion of its Commitment Percentage and Commitment and the same portion of
the Loans at the time owing to it, the Revolving Credit Notes held by it and its
participating interest in the risk relating to any Letters of Credit); provided
                                                                       --------
that (a) the Agent and the Borrower each shall have the right to approve any
Eligible Assignee, which approval shall not be unreasonably withheld or delayed,
it being agreed that the Agent and the Borrower must approve or reject a
proposed Eligible Assignee within seven (7) days of receiving a written request
from any Bank for such approval (provided that the request for approval, and the
                                 --------
envelope in which it is delivered, is conspicuously marked with the following
legend: "REQUEST FOR APPROVAL -- TIME SENSITIVE -- MUST RESPOND WITHIN SEVEN (7)
DAYS") and if the Agent or the Borrower fails to respond within such seven (7)
day period, such request for approval shall be deemed approved by the Agent or
the Borrower, or both, as the case may be, (b) each such assignment shall be of
a constant, and not a varying, percentage of all the assigning Bank's rights and
obligations under this Agreement, (c) subject to the provisions of (S)2.7
hereof, each Bank shall have at all times an amount of its Commitment of not
less than $10,000,000 and (d) the parties to such assignment shall execute and
deliver to the Agent, for recording in the Register (as hereinafter defined), an
assignment and assumption, substantially in the form of Exhibit F hereto (an
                                                        ---------
"Assignment and Assumption"), together with any Revolving Credit Notes subject
to such assignment. Upon such execution, delivery, acceptance and recording,
from and after the effective date specified in each Assignment and Assumption,
which

                                      -81-
<PAGE>
 
which effective date shall be at least two (2) Business Days after the execution
thereof unless otherwise agreed by the Agent (provided any assignee has assumed
the obligation to fund any outstanding Eurodollar Rate Loans), (i) the assignee
thereunder shall be a party hereto and, to the extent provided in such
Assignment and Assumption, have the rights and obligations of a Bank hereunder
and thereunder, and (ii) the assigning Bank shall, to the extent provided in
such assignment and upon payment to the Agent of the registration fee referred
to in (S)20.3, be released from its obligations under this Agreement. Any such
Assignment and Assumption shall run to the benefit of the Borrower and a copy of
any such Assignment and Assumption shall be delivered by the Assignor to the
Borrower.

           (S)20.2. Certain Representations and Warranties; Limitations;
                    ----------------------------------------------------
Covenants. By executing and delivering an Assignment and Assumption, the parties
- ----------
to the assignment thereunder confirm to and agree with each other and the other
parties hereto as follows: (a) other than the representation and warranty that
it is the legal and beneficial owner of the interest being assigned thereby free
and clear of any adverse claim, the assigning Bank makes no representation or
warranty and assumes no responsibility with respect to any statements,
warranties or representations made in or in connection with this Agreement or
the execution, legality, validity, enforceability, genuineness, sufficiency or
value of this Agreement, the other Loan Documents or any other instrument or
document furnished pursuant hereto; (b) the assigning Bank makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of the Borrower and its Subsidiaries or the Guarantor or any
other Person primarily or secondarily liable in respect of any of the
Obligations, or the performance or observance by the Borrower and its
Subsidiaries or the Guarantor or any other Person primarily or secondarily
liable in respect of any of the Obligations of any of their obligations under
this Agreement or any of the other Loan Documents or any other instrument or
document furnished pursuant hereto or thereto; (c) such assignee confirms that
it has received a copy of this Agreement, together with copies of the most
recent financial statements referred to in (S)7.4 and (S)8.4 and such other
documents and information as it has deemed appropriate to make its own credit
analysis and decision to enter into such Assignment and Assumption; (d) such
assignee will, independently and without reliance upon the assigning Bank, the
Agent or any other Bank and based on such documents and information as it shall
deem appropriate at the time, continue to make its own credit decisions in
taking or not taking action under this Agreement; (e) such assignee represents
and warrants that it is an Eligible Assignee; (f) such assignee appoints and
authorizes the Agent to take such action as agent on its behalf and to exercise
such powers under this Agreement and the other Loan Documents as are delegated
to the Agent by the terms hereof or thereof, together with such powers as are
reasonably incidental thereto; (g) such assignee agrees that it will perform in
accordance with their terms all of the obligations that by the terms of this
Agreement are required to be performed by it as a Bank; (h) such assignee
represents and warrants that it is legally authorized to enter into such
Assignment and Assumption; and (i) such assignee acknowledges that it has made
arrangements with the assigning Bank satisfactory to such assignee with respect
to its pro rata share of Letter of Credit Fees in respect of outstanding Letters
of Credit.

                                      -82-
<PAGE>
 
           (S)20.3. Register. The Agent shall maintain a copy of each
                    --------
Assignment and Assumption delivered to it and a register or similar list (the
"Register") for the recordation of the names and addresses of the Banks and the
Commitment Percentages of, and principal amount of the Loans owing to, the Banks
from time to time. The entries in the Register shall be conclusive, in the
absence of manifest error, and the Borrower, the Agent and the Banks may treat
each Person whose name is recorded in the Register as a Bank hereunder for all
purposes of this Agreement. The Register shall be available for inspection by
the Borrower and the Banks at any reasonable time and from time to time upon
reasonable prior notice. Upon each such recordation, the assigning Bank agrees
to pay to the Agent a registration fee in the sum of $2,500.

           (S)20.4. New Revolving Credit Notes. Upon its receipt of an
                    --------------------------
Assignment and Assumption executed by the parties to such assignment, together
with each Revolving Credit Note subject to such assignment, the Agent shall (a)
record the information contained therein in the Register, and (b) give prompt
notice thereof to the Borrower and the Banks (other than the assigning Bank).
Unless done simultaneously with the Assignment and Assumption, within two (2)
Business Days after receipt of such notice, the Borrower, at its own expense,
(i) shall execute and deliver to the Agent, in exchange for each surrendered
Revolving Credit Note, a new Revolving Credit Note to the order of such Eligible
Assignee in an amount equal to the amount assumed by such Eligible Assignee
pursuant to such Assignment and Assumption and, if the assigning Bank has
retained some portion of its obligations hereunder, a new Revolving Credit Note
to the order of the assigning Bank in an amount equal to the amount retained by
it hereunder and (ii) shall deliver an opinion from counsel to the Borrower in
substantially the form delivered on the Closing Date pursuant to (S)12.9 as to
such new Revolving Credit Notes. Such new Revolving Credit Notes shall provide
that they are replacements for the surrendered Revolving Credit Notes, shall be
in an aggregate principal amount equal to the aggregate principal amount of the
surrendered Revolving Credit Notes, shall be dated the effective date of such
Assignment and Assumption and shall otherwise be in substantially the form of
the assigned Revolving Credit Notes. The surrendered Revolving Credit Notes
shall be canceled and returned to the Borrower.

           (S)20.5. Participations. Each Bank may sell participations to one
                    --------------
or more banks or other entities in all or a portion of such Bank's rights and
obligations under this Agreement and the other Loan Documents; provided that (a)
each such participation shall be in an amount of not less than $10,000,000, (b)
any such sale or participation shall not affect the rights and duties of the
selling Bank hereunder to the Borrower and the Agent and the Bank shall continue
to exercise all approvals, disapprovals and other functions of a Bank, (c) the
only rights granted to the participant pursuant to such participation
arrangements with respect to waivers, amendments or modifications of, or
approvals under, the Loan Documents shall be the rights to approve waivers,
amendments or modifications that would reduce the principal of or the interest
rate on any Loans, extend the term or increase the amount of the Commitment of
such Bank as it relates to such participant, reduce the amount of any fees to
which such participant is entitled or extend any regularly scheduled payment
date for principal or interest, and (d) no participant shall 

                                      -83-
<PAGE>
 
have the right to grant further participations or assign its rights, obligations
or interests under such participation to other Persons without the prior written
consent of the Agent.

           (S)20.6. Pledge by Lender. Notwithstanding any other provision of
                    ----------------
this Agreement, any Bank at no cost to the Borrower may at any time pledge all
or any portion of its interest and rights under this Agreement (including all or
any portion of its Revolving Credit Notes) to any of the twelve Federal Reserve
Banks organized under (S)4 of the Federal Reserve Act, 12 U.S.C. (S)341. No such
pledge or the enforcement thereof shall release the pledgor Bank from its
obligations hereunder or under any of the other Loan Documents.

           (S)20.7. No Assignment by Borrower. The Borrower shall not assign
                    -------------------------
or transfer any of its rights or obligations under any of the Loan Documents
without prior Unanimous Bank Approval.

           (S)20.8. Disclosure. The Borrower agrees that, in addition to
                    ----------
disclosures made in accordance with standard banking practices, any Bank may
disclose information obtained by such Bank pursuant to this Agreement to
assignees or participants and potential assignees or participants hereunder. Any
such disclosed information shall be treated by any assignee or participant with
the same standard of confidentiality set forth in (S)8.10 hereof.

           (S)20.9. Syndication. The Borrower acknowledges that each of the
                    -----------
Agent and the Arranger intends, and shall have the right, by itself or through
its Affiliates, to syndicate or enter into co-lending arrangements with respect
to the Loans and the Total Commitment pursuant to this (S)20, and the Borrower
agrees to cooperate with the Agent's and the Arranger's and their Affiliate's
syndication and/or co-lending efforts, such cooperation to include, without
limitation, the provision of information reasonably requested by potential
syndicate members.

           (S)21.   NOTICES, ETC. Except as otherwise expressly provided in
                    ------------
this Agreement, all notices and other communications made or required to be
given pursuant to this Agreement or the Revolving Credit Notes or any Letter of
Credit Applications shall be in writing and shall be delivered in hand, mailed
by United States registered or certified first class mail, postage prepaid, sent
by overnight courier, or sent by facsimile and confirmed by delivery via courier
or postal service, addressed as follows:

                       (a)   if to the Borrower or any Guarantor, at Boston
Properties, Inc., 8 Arlington Street, Boston, Massachusetts 02116, Attention:
Mr. Edward H. Linde, President and Chief Executive Officer, with a copy to the
General Counsel of BPLP at the address for the Borrower set forth above and to
Ross D. Gillman, Esq., Goodwin, Procter & Hoar LLP, Exchange Place, Boston,
Massachusetts 02109, or to such other address for notice as the Borrower or any
Guarantor shall have last furnished in writing to the Agent;

                                      -84-
<PAGE>
 
                       (b)   if to the Agent, to the Real Estate Finance
Department at 100 Federal Street, Boston, Massachusetts 02110, with a copy to
Robert C. Avil, Vice President, BankBoston, N.A., 115 Perimeter Center Place,
Suite 500, Atlanta, Georgia 30346, or such other address for notice as the Agent
shall have last furnished in writing to the Borrower, with a copy to Michael J.
Haroz, Esq., Goulston & Storrs, 400 Atlantic Avenue, Boston, Massachusetts 
02110-3333, or at such other address for notice as the Agent shall last have
furnished in writing to the Person giving the notice; and

                       (c)   if to any Bank, at such Bank's address set forth on
                                                                              --
Schedule 1.3 hereto, or such other address for notice as such Bank shall have
- --------
last furnished in writing to the Person giving the notice.

Any such notice or demand shall be deemed to have been duly given or made and to
have become effective (i) if delivered by hand, overnight courier, or facsimile
to the party to which it is directed, at the time of the receipt thereof by such
party or the sending of such facsimile and (ii) if sent by registered or
certified first-class mail, postage prepaid, on the third Business Day following
the mailing thereof.

           (S)22.   BPLP AS AGENT FOR THE BORROWERS. Each Borrower (other
                    -------------------------------
than BPLP) hereby appoints BPLP as its agent with respect to the receiving and
giving of any notices, requests, instructions, reports, certificates (including,
without limitation, compliance certificates), schedules, revisions, financial
statements or any other written or oral communications hereunder. The Agent and
each Bank is hereby entitled to rely on any communications given or transmitted
by BPLP as if such communication were given or transmitted by each and every
Borrower; provided however, that any communication given or transmitted by any
Borrower other than BPLP shall be binding with respect to such Borrower. Any
communication given or transmitted by the Agent or any Bank to BPLP shall be
deemed given and transmitted to each and every Borrower.

           (S)23.   GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE. THIS
                    --------------------------------------------------
AGREEMENT AND EACH OF THE OTHER LOAN DOCUMENTS, EXCEPT AS OTHERWISE SPECIFICALLY
PROVIDED THEREIN, ARE CONTRACTS UNDER THE LAWS OF THE COMMONWEALTH OF
MASSACHUSETTS AND SHALL FOR ALL PURPOSES BE CONSTRUED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF SUCH COMMONWEALTH (EXCLUDING THE LAWS APPLICABLE TO
CONFLICTS OR CHOICE OF LAW). EACH OF THE BORROWER AND THE GUARANTOR AND THEIR
RESPECTIVE SUBSIDIARIES AGREES THAT ANY SUIT FOR THE ENFORCEMENT OF THIS
AGREEMENT OR ANY OF THE OTHER LOAN DOCUMENTS MAY BE BROUGHT IN THE COURTS OF THE
COMMONWEALTH OF MASSACHUSETTS SITTING IN SUFFOLK COUNTY OR ANY FEDERAL COURT
SITTING IN THE EASTERN DISTRICT OF MASSACHUSETTS AND CONSENTS TO THE NON-
EXCLUSIVE JURISDICTION OF SUCH COURTS AND THE SERVICE OF PROCESS IN ANY SUCH
SUIT BEING MADE UPON THE BORROWER OR THE GUARANTOR AND THEIR RESPECTIVE
SUBSIDIARIES BY MAIL AT THE ADDRESS SPECIFIED IN (S)21. THE BORROWER AND THE
GUARANTOR AND THEIR RESPECTIVE 

                                      -85-
<PAGE>
 
SUBSIDIARIES HEREBY WAIVE ANY OBJECTION THAT ANY OF THEM MAY NOW OR HEREAFTER
HAVE TO THE VENUE OF ANY SUCH SUIT OR ANY SUCH COURT OR THAT SUCH SUIT IS
BROUGHT IN AN INCONVENIENT COURT.

           (S)24. HEADINGS. The captions in this Agreement are for
                  --------
convenience of reference only and shall not define or limit the provisions
hereof.

           (S)25. COUNTERPARTS. This Agreement and any amendment hereof may
                  ------------
be executed in several counterparts and by each party on a separate counterpart,
each of which when so executed and delivered shall be an original, and all of
which together shall constitute one instrument. In proving this Agreement it
shall not be necessary to produce or account for more than one such counterpart
signed by the party against whom enforcement is sought.

           (S)26. ENTIRE AGREEMENT, ETC. The Loan Documents and any other
                  ---------------------
documents executed in connection herewith or therewith express the entire
understanding of the parties with respect to the transactions contemplated
hereby. Neither this Agreement nor any term hereof may be changed, waived,
discharged or terminated, except as provided in (S)27.

           (S)27. WAIVER OF JURY TRIAL AND CERTAIN DAMAGE CLAIMS. EXCEPT TO
                  ----------------------------------------------
THE EXTENT EXPRESSLY PROHIBITED BY LAW, THE BORROWER AND THE GUARANTOR AND THEIR
RESPECTIVE SUBSIDIARIES HEREBY WAIVE THEIR RESPECTIVE RIGHTS TO A JURY TRIAL
WITH RESPECT TO ANY ACTION OR CLAIM ARISING OUT OF ANY DISPUTE IN CONNECTION
WITH THIS AGREEMENT, THE REVOLVING CREDIT NOTES OR ANY OF THE OTHER LOAN
DOCUMENTS, ANY RIGHTS OR OBLIGATIONS HEREUNDER OR THEREUNDER OR THE PERFORMANCE
OF SUCH RIGHTS AND OBLIGATIONS. EXCEPT TO THE EXTENT EXPRESSLY PROHIBITED BY
LAW, THE BORROWER AND THE GUARANTOR AND THEIR RESPECTIVE SUBSIDIARIES HEREBY
WAIVE ANY RIGHT ANY OF THEM MAY HAVE TO CLAIM OR RECOVER IN ANY LITIGATION
REFERRED TO IN THE PRECEDING SENTENCE ANY SPECIAL, EXEMPLARY, PUNITIVE OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES OTHER THAN, OR IN ADDITION TO, ACTUAL
DAMAGES, INCLUDING ANY DAMAGES PURSUANT TO M.G.L. C. 93A ET SEQ. EACH OF THE
BORROWER AND THE GUARANTOR AND THEIR RESPECTIVE SUBSIDIARIES (A) CERTIFIES THAT
NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY BANK OR THE AGENT HAS REPRESENTED,
EXPRESSLY OR OTHERWISE, THAT SUCH BANK OR THE AGENT WOULD NOT, IN THE EVENT OF
LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVERS AND (B) ACKNOWLEDGE THAT THE
AGENT AND THE BANKS HAVE BEEN INDUCED TO ENTER INTO THIS AGREEMENT AND THE OTHER
LOAN DOCUMENTS TO WHICH THEY ARE PARTIES BY, AMONG OTHER THINGS, THE WAIVERS AND
CERTIFICATIONS CONTAINED HEREIN.

                                      -86-
<PAGE>
 
           (S)28. CONSENTS, AMENDMENTS, WAIVERS, ETC. Except as otherwise
                  ----------------------------------
expressly provided in this Agreement, any consent or approval required or
permitted by this Agreement may be given, and any term of this Agreement or of
any of the other Loan Documents may be amended, and the performance or
observance by the Borrower or the Guarantor or any of their respective
Subsidiaries of any terms of this Agreement or the other Loan Documents or the
continuance of any Default or Event of Default may be waived (either generally
or in a particular instance and either retroactively or prospectively) with, but
only with, the written consent of the Majority Banks.

           Notwithstanding the foregoing, Unanimous Bank Approval shall be
required for any amendment, modification or waiver of this Agreement that:

                                          (i) reduces or forgives any principal
                               of any unpaid Loan or any interest thereon
                               (including any interest "breakage" costs) or any
                               fees due any Bank hereunder, or permits any
                               prepayment not otherwise permitted hereunder; or

                                         (ii) changes the unpaid principal
                               amount of, or the rate of interest on, any Loan;
                               or

                                        (iii) changes the date fixed for any
                               payment of principal of or interest on any Loan
                               (including, without limitation, any extension of
                               the Maturity Date) or any fees payable hereunder;
                               or

                                         (iv) changes the amount of any Bank's
                               Commitment (other than pursuant to an assignment
                               permitted under (S)20.1 hereof) or increases the
                               amount of the Total Commitment; or

                                         (v)  modifies any provision herein or
                               in any other Loan Document which by the terms
                               thereof expressly requires Unanimous Bank
                               Approval; or

                                        (vi)  changes the definitions of
                               Majority Banks, Required Banks or Unanimous Bank
                               Approval. No waiver shall extend to or affect any
                               obligation not expressly waived or impair any
                               right consequent thereon. No course of dealing or
                               delay or omission on the part of the Agent or the
                               Banks or any Bank in exercising any right shall
                               operate as a waiver thereof or otherwise be
                               prejudicial to such right or any other rights of
                               the Agent or the Banks. No notice to or demand
                               upon the Borrower shall entitle the Borrower to
                               other or further notice or demand in similar or
                               other circumstances.

           Notwithstanding the foregoing, the Required Banks shall be required
for any amendment, modification or waiver of this agreement that:

                                      -87-
<PAGE>
 
                                          (i) amends any of the covenants
                               contained in (S)10.1 through (S)10.7, inclusive,
                               hereof, or

                                         (ii) amends any of the provisions
                               governing funding contained in (S)2 hereof, or

                                        (iii) changes the rights, duties or
                               obligations of the Agent specified in (S)16
                               hereof (provided that no amendment or
                               modification to such (S)16 or to the fee payable
                               to the Agent under this Agreement may be made
                               without the prior written consent of the Agent).


           (S)29. SEVERABILITY. The provisions of this Agreement are
                  ------------
severable, and if any one clause or provision hereof shall be held invalid or
unenforceable in whole or in part in any jurisdiction, then such invalidity or
unenforceability shall affect only such clause or provision, or part thereof, in
such jurisdiction, and shall not in any manner affect such clause or provision
in any other jurisdiction, or any other clause or provision of this Agreement in
any jurisdiction.


                  (Remainder of page intentionally left blank)

                                      -88-
<PAGE>
 
           IN WITNESS WHEREOF, the undersigned have duly executed this Agreement
as a sealed instrument as of the date first set forth above.

                            BANKBOSTON, N.A.
                            individually and as Agent


                            By: ____________________________
                            Name:  Robert C. Avil
                            Title: Vice President


                      (Signatures continued on next pages)

                                      -89-
<PAGE>
 
                                   8 Arlington Street*
                                   -------------------

                                   THE ATLANTIC MONTHLY TRUST


                                   By:____________________________________
                                        Mortimer B. Zuckerman, as Trustee 
                                        and not individually


                                   32 Hartwell Avenue, Lexington, MA
                                   ---------------------------------

                                   MBZ-LEX TRUST
                                   
                                   
                                   By:____________________________________
                                        Mortimer B. Zuckerman, as Trustee 
                                        and not individually
                                   
                                   
                                   By:____________________________________
                                        Edward H. Linde, as Trustee and 
                                        not individually


                                   Waltham Office Center, Waltham, MA
                                   ----------------------------------

                                   ZEE EM TRUST II
                                   
                                   
                                   By:____________________________________
                                        Mortimer B. Zuckerman, as Trustee 
                                        and not individually
                                   
                                   
                                   By:____________________________________
                                        Edward H. Linde, as Trustee and 
                                        not individually
         
                       (Signatures continued on next page)

- ---------------------------
* The designation of the specific Real Estate Asset or Assets owned by any 
signatory to this Agreement or any other Loan Document is for informational 
purposes only and does not in any way limit the joint and several liability of 
each Borrower, for so long as it is a Borrower, for the Obligations.

                                      -90-
<PAGE>
 
                                 204 Second Avenue, Waltham, MA
                                 ------------------------------

                                 WP TRUST
                                 
                                 
                                 By:____________________________________
                                      Edward H. Linde, as Trustee and 
                                      not individually


                                 170 Tracer Lane, Waltham, MA
                                 ----------------------------

                                 TRACER LANE TRUST
                                 
                                 
                                 By:____________________________________
                                      Edward H. Linde, as Trustee and 
                                      not individually
                                 
                                 
                                 By:____________________________________
                                      Mortimer B. Zuckerman, as Trustee 
                                      and not individually


                                 33 Hayden Avenue, Lexington, MA
                                 -------------------------------

                                 HAYDEN OFFICE TRUST
                                 
                                 
                                 By:____________________________________
                                      Edward H. Linde, as Trustee and 
                                      not individually
                                 
                                 
                                 By:____________________________________
                                      Mortimer B. Zuckerman, as Trustee 
                                      and not individually

                       (Signatures continued on next page)

                                      -91-
<PAGE>
 
                                 Lexington Office Park, 420-430 Bedford Street,
                                 ----------------------------------------------
                                 Lexington, MA
                                 -------------

                                 ELANDZEE TRUST
                                 
                                 
                                 By:____________________________________
                                      Mortimer B. Zuckerman, as Trustee 
                                      and not individually


                                 By:____________________________________
                                      Edward H. Linde, as Trustee and 
                                      not individually


                                 40-46 Harvard Street, Westwood, MA
                                 ----------------------------------

                                 40-46 HARVARD STREET TRUST


                                 By:____________________________________
                                      Mortimer B. Zuckerman, as Trustee 
                                      and not individually
                                 
                                 
                                 By:____________________________________
                                      Edward H. Linde, as Trustee and 
                                      not individually


                                 17 Hartwell Avenue, Lexington, MA
                                 ---------------------------------

                                 ZEE BEE TRUST II


                                 By:____________________________________
                                      Mortimer B. Zuckerman, as Trustee 
                                      and not individually

                       (Signatures continued on next page)

                                      -92-
<PAGE>
 
                                   One Cambridge Center, Cambridge, MA
                                   -----------------------------------

                                   ONE CAMBRIDGE CENTER TRUST


                                    By:____________________________________
                                         Mortimer B. Zuckerman, as Trustee 
                                         and not individually


                                    By:____________________________________
                                         David Barrett, as Trustee and 
                                         not individually


                                    By:____________________________________
                                         Edward H. Linde, as Trustee and 
                                         not individually
                                    
                                    
                                    Three Cambridge Center, Cambridge, MA
                                    -------------------------------------

                                    THREE CAMBRIDGE CENTER TRUST


                                    By:____________________________________
                                         Mortimer B. Zuckerman, as Trustee 
                                         and not individually
                                    
                                    
                                    By:____________________________________
                                         David Barrett, as Trustee and 
                                         not individually
                                    
                                    
                                    By:____________________________________
                                         Edward H. Linde, as Trustee and 
                                         not individually

                       (Signatures continued on next page)

                                      -93-
<PAGE>
 
                                    Eleven Cambridge Center, Cambridge, MA
                                    --------------------------------------

                                    ELEVEN CAMBRIDGE CENTER TRUST


                                    By:____________________________________
                                         Mortimer B. Zuckerman, as Trustee 
                                         and not individually
                                    
                                    
                                    By:____________________________________
                                         David Barrett, as Trustee and 
                                         not individually
                                    
                                    
                                    By:____________________________________
                                         Edward H. Linde, as Trustee and 
                                         not individually
                                    
                                    
                                    Fourteen Cambridge Center, Cambridge, MA
                                    ----------------------------------------

                                    FOURTEEN CAMBRIDGE CENTER TRUST


                                    By:____________________________________
                                         Mortimer B. Zuckerman, as Trustee 
                                         and not individually
                                    
                                    
                                    By:____________________________________
                                         David Barrett, as Trustee and 
                                         not individually
                                    
                                    
                                    By:____________________________________
                                         Edward H. Linde, as Trustee and 
                                         not individually

                       (Signatures continued on next page)

                                      -94-
<PAGE>
 
                         500 E Street, S.W., Washington, D.C.
                         ------------------------------------
                         
                         SCHOOL STREET ASSOCIATES LIMITED PARTNERSHIP
                         
                         By:   Boston Properties LLC, its sole general partner
                               
                               By:  Boston Properties Limited
                                    Partnership, its managing member
                                    
                                    By:        Boston Properties, Inc., its
                                               general partner
                                    
                                               By:______________(SEAL)
                                                     Edward H. Linde
                                                     President and Chief
                                                     Executive Officer


                         Democracy Center, Bethesda, MD
                         ------------------------------

                         DEMOCRACY ASSOCIATES LIMITED PARTNERSHIP
                         
                         By:  Boston Properties LLC, its general partner
                              
                              By:  Boston Properties Limited
                                   Partnership, its managing member
                                   
                                   By:        Boston Properties, Inc., its
                                              general partner
                                   
                                              By:___________________(SEAL)
                                                    Edward H. Linde
                                                    President and Chief
                                                    Executive Officer

                       (Signatures continued on next page)

                                      -95-
<PAGE>
 
                         1950 Stanford Court, Building One (MD 1),
                         -----------------------------------------
                         Landover, MD
                         ------------
                         
                         MARYLAND 50 BUILDING I ASSOCIATES LIMITED PARTNERSHIP
                         
                         By:  Boston Properties LLC, its general partner
                              
                              By:       Boston Properties Limited
                                        Partnership, its managing member
                              
                                        By:        Boston Properties, Inc., its
                                                   general partner
                              
                                                   By:___________________(SEAL)
                                                         Edward H. Linde
                                                         President and Chief
                                                         Executive Officer
                         
                         
                         6201 Columbia Park Road, Building Two (MD2),
                         --------------------------------------------
                         Landover, MD
                         ------------
                         
                         MARYLAND 50 BUILDING II ASSOCIATES LIMITED PARTNERSHIP
                         
                         By:  Boston Properties LLC, its general partner
                              
                              By:       Boston Properties Limited
                                        Partnership, its managing member
                              
                                        By:        Boston Properties, Inc., its
                                                   general partner
                              
                                                   By:___________________(SEAL)
                                                         Edward H. Linde
                                                         President and Chief
                                                         Executive Officer

                       (Signatures continued on next page)

                                      -96-
<PAGE>
 
                         2000 South Club Drive, Building Three (MD3),
                         --------------------------------------------
                         Landover, MD
                         ------------
                         
                         MARYLAND 50 BUILDING III ASSOCIATES LIMITED PARTNERSHIP
                         
                         By:  Boston Properties LLC, its general partner
                              
                              By:       Boston Properties Limited
                                        Partnership, its managing member
                              
                                        By:        Boston Properties, Inc., its
                                                   general partner
                              
                                                   By:___________________(SEAL)
                                                         Edward H. Linde
                                                         President and Chief
                                                         Executive Officer


                         Long Wharf Marriott, Boston, MA
                         -------------------------------

                         DOWNTOWN BOSTON PROPERTIES TRUST


                         By:____________________________________
                              Edward H. Linde, as Trustee and 
                              not individually
                         
                         
                         By:____________________________________
                              Mortimer B. Zuckerman, as Trustee 
                              and not individually

                       (Signatures continued on next page)

                                      -97-
<PAGE>
 
                                       Cambridge Center Marriott, Cambridge, MA
                                       ----------------------------------------

                                       TWO CAMBRIDGE CENTER TRUST


                                       By:____________________________________
                                            Mortimer B. Zuckerman, as Trustee 
                                            and not individually


                                       By:____________________________________
                                            Edward H. Linde, as Trustee and 
                                            not individually


                                       By:____________________________________
                                            David Barrett, as Trustee and 
                                            not individually


                                       195 West Street, Waltham, MA
                                       ----------------------------

                                       25-33 Dartmouth Street, Westwood, MA
                                       ------------------------------------

                                       7435 Boston Boulevard, Building One,
                                       ------------------------------------
                                       Springfield, VA
                                       ---------------

                                      7451 Boston Boulevard, Building Two,
                                      ------------------------------------
                                      Springfield, VA
                                      ---------------

                                      7374 Boston Boulevard, Building Four,
                                      -------------------------------------
                                      Springfield, VA
                                      ---------------

                                      8000 Grainger Court, Building Five,
                                      -----------------------------------
                                      Springfield, VA
                                      ---------------

                                      7500 Boulevard, Building Six,
                                      -----------------------------
                                      Springfield, VA
                                      ---------------

                                      7501 Boston Boulevard, Building Seven,
                                      --------------------------------------
                                      Springfield, VA
                                      ---------------
                                      
                                      7601 Boston Boulevard, Building Eight,
                                      --------------------------------------
                                      Springfield, VA
                                      ---------------

                       (Signatures continued on next page)

                                      -98-
<PAGE>
 
                                      7600 Boston Boulevard, Building Nine,
                                      -------------------------------------
                                      Springfield, VA
                                      ---------------

                                      7375 Boston Boulevard, Building Ten,
                                      ------------------------------------
                                      Springfield, VA
                                      ---------------
                                      
                                      8000 Corporate Court, Building Eleven,
                                      --------------------------------------
                                      Springfield, VA
                                      ---------------
                                      
                                      7700 Boston Boulevard, Building Twelve,
                                      ---------------------------------------
                                      Springfield, VA
                                      ---------------

                                      38 Cabot Boulevard, Bucks County, PA
                                      ------------------------------------

                                      2391 West Winton Avenue, Hayward, CA
                                      ------------------------------------

                                      365 Herndon Parkway (Sugarland I),
                                      ---------------------------------
                                      Herndon, VA
                                      -----------

                                      397 Herndon Parkway (Sugarland II),
                                      -----------------------------------
                                      Herndon, VA
                                      -----------

                                      164 Lexington Road, Billerica, MA
                                      ---------------------------------

                                      BOSTON PROPERTIES LIMITED PARTNERSHIP
                                      
                                      
                                      By:  Boston Properties, Inc., its sole 
                                           general partner
                                           
                                           By:_________________________(SEAL)
                                                 Edward H. Linde
                                                 President and Chief Executive 
                                                 Officer

                                      -99-
<PAGE>
 
                                  Schedule 1.1
                                  ------------

                            Borrowing Base Properties
                            -------------------------

                                     -100-
<PAGE>
 
<TABLE> 
<CAPTION> 
                                  Schedule 1.3

Bank                              Commitment Amount                  Commitment Percentage
- ----                              -----------------                  ---------------------
<S>                               <C>                                <C> 
BankBoston, N.A.                    $300,000,000.00                           100%
100 Federal Street
Boston, MA 02110

TOTAL                               $300,000,000.00                           100%
</TABLE> 

                                     -101-
