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                                                                     Exhibit 8.1
                          GOODWIN, PROCTER & HOAR LLP
                              COUNSELLORS AT LAW
                                EXCHANGE PLACE
                       BOSTON, MASSACHUSETTS 02109-2881



                               December 21, 1998



Boston Properties, Inc.
8 Arlington Street
Boston, Massachusetts  02116

Ladies and Gentlemen:

     We have acted as counsel to Boston Properties, Inc., a Delaware corporation
(the "Company") in connection with the preparation of a registration statement
(the "Registration Statement") filed with the Securities and Exchange Commission
on Form S-3, as amended, relating to an indeterminate amount of Preferred Stock,
Common Stock and Warrants (as such terms are defined in the Registration
Statement) authorized for issuance under the Company's Amended and Restated
Certificate of Incorporation (the "Certificate"), with an aggregate public
offering price of up to $1,500,000,000 (the "Offering"). You have requested our
opinion on certain federal income tax matters in connection with the Offering.

     Capitalized terms not defined herein shall have the same meaning as in the
Registration Statement.

     In rendering the following opinion, we have examined the Amended and
Restated Certificate of Incorporation (the "Articles") and Bylaws of the
Company, and such other records, certificates and documents as we have deemed
necessary or appropriate for purposes of rendering the opinion set forth herein
(collectively, the "Documents").  We have reviewed the investment activities,
operations and governance of the Company and its subsidiaries.  We have relied
upon representations of duly appointed officers of the Company and the Operating
Partnership (including without limitation, representations contained in a letter
dated as of the date hereof (the "Officer's Certificate")), principally relating
to the Company's organization and operations. We assume that each such
representation is and will be true, correct and complete and that all
representations that speak in the future, or to the intention, or to the best of
the belief and knowledge of any person(s) or party(ies) are and will be true,
correct and complete as if made without such qualification. Nothing has come to
our attention which would cause us to believe that any of such representations
are untrue, incorrect or incomplete. We assume that the

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Boston Properties, Inc.
December 21, 1998
Page 2
 
Company will be operated in accordance with the applicable laws and the terms
and conditions of applicable documents. We have also reviewed the Registration
Statement, the Amended and Restated Agreement of Limited Partnership of the
Operating Partnership, and such other documents as we have deemed appropriate.
In addition, we have relied upon certain additional facts and assumptions
described below.

     In rendering the opinion set forth herein, we have assumed (i) the
genuineness of all signatures on documents we have examined, (ii) the
authenticity of all documents submitted to us as originals, (iii) the conformity
to the original documents of all documents submitted to us as copies, (iv) the
conformity of final documents to all documents submitted to us as drafts, (v)
the authority and capacity of the individual or individuals who executed any
such documents on behalf of any person, (vi) the accuracy and completeness of
all records made available to us, and (vii) the factual accuracy of all
representations, warranties and other statements made by all parties.  In
addition, we assume that all interests in the Operating Partnership have been
and will be issued in a transaction (or transactions) that are not required to
be registered under the Securities Act of 1933 and that no interest in the
Operating Partnership offered for sale outside the United States would have been
required to be registered under the Securities Act of 1933 if such interest had
been offered for sale within the United States.  We have further assumed that
during its short 1997 taxable year ending December 31, 1997 and subsequent
taxable years, the Company has operated and will operate in such a manner that
has made and will make the representations contained in the Officer's
Certificate true for all such years, and that the Company and its subsidiaries
will not make any amendments to its organizational documents after the date of
this opinion that would affect the Company's qualification as a real estate
investment trust for any taxable year.  For purposes of our opinion, we have
made no independent investigation of the facts contained in the documents and
assumptions set forth above, the representations set forth in the Officer's
Certificate, or the Registration Statement.  No facts have come to our
attention, however, that would cause us to question the accuracy and
completeness of such facts or documents in a material way.

     The discussion and conclusion set forth below are based upon the Code, the
Income Tax Regulations and Procedure and Administration Regulations promulgated
thereunder and existing administrative and judicial interpretation thereof, all
of which are subject to change.  No assurance can therefore be given that the
federal income tax consequences described below will not be altered in the
future.  Based on the documents and assumptions set forth above, the
representations set forth in the Officer's Certificate and provided that the
Company continues to meet the applicable asset composition, source of income,
shareholder diversification, distribution, and other requirements of the Code
necessary for a corporation to qualify as a real 
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Boston Properties, Inc.
December 21, 1998
Page 3
 
estate investment trust, we are of the opinion that:

     (1) Commencing with the Company's initial taxable year ended December 31,
1997, the Company has been operated and organized in conformity with the
requirements for qualification as a "real estate investment trust" under the
Code, and its method of operation, as described in the Officers Certificate,
will enable it to continue to meet the requirements for qualification as a "real
estate investment trust" under the Code, and

     (2) The information in the Registration Statement under the caption
"Certain Federal Income Tax Considerations" to the extent that it constitutes
matters of law or legal conclusions, have been reviewed by us and is correct in
all material respects, and our opinion set forth in such discussion is
confirmed.

     We will not review on a continuing basis the Company's compliance with the
documents or assumptions set forth above, or the representations set forth in
the Officer's Certificate. Accordingly, no assurance can be given that the
actual results of the Company's operations for any given taxable year will
satisfy the requirements for qualification and taxation as a real estate
investment trust under the Code.  The ability of the Company to continue to meet
the requirements for qualification and taxation as a real estate investment
trust will be dependent upon the Company's ability to continue to meet in each
year the applicable asset composition, source of income, shareholder
diversification, distribution, and other requirements of the Code necessary for
a corporation to qualify as a real estate investment trust.  The foregoing
opinions are limited to the federal income tax matters addressed herein, and no
other opinions are rendered with respect to other federal tax matters or to any
issues arising out of the tax laws of any state or locality.  We express no
opinion with respect to the transactions described herein other than those
expressly set forth herein.  You should recognize that our opinion is not
binding on the Internal Revenue Service and that the Internal Revenue Service
may disagree with the opinion contained herein.  Although we believe that our
opinion will be sustained if challenged, there is no guarantee that this will be
the case.  Except as specifically discussed above, the opinion expressed herein
is based upon the laws that currently exist.  Consequently, future changes in
the law may cause the federal income tax treatment of the transactions herein to
be materially and adversely different from that described above.  This opinion
may be relied on solely by you in connection with the Offering.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.  We also consent to the references to Goodwin, Procter &
Hoar,  LLP under the caption "Certain Federal Income Tax Considerations" in the
Registration Statement.  In giving this consent, we do not admit that we are in
the category of persons whose consent is required by
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Boston Properties, Inc.
December 21, 1998
Page 4
 
Section 7 of the Securities Act of 1933, as amended, or the rules and
regulations promulgated thereunder by the Securities and Exchange Commission.

                                    Very truly yours,




                                    /s/ Goodwin, Procter & Hoar  LLP
                                    GOODWIN, PROCTER & HOAR  LLP
