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                                                                     Exhibit 5.1

                    [BALLARD SPAHR ANDREWS & INGERSOLL, LLP]

                                November 19, 2001


AMB Property Corporation
Pier 1, Bay 1
San Francisco, California 94111


       Re:    AMB Property Corporation, a Maryland corporation (the "Company")
              -- Registration Statement on Form S-3 pertaining to One Million
              Five Hundred Sixty Thousand Six Hundred Ninety-Seven (1,560,697)
              shares (the "Shares") of common stock, par value one cent ($.01)
              per share (the "Common Stock") of the Company, of which
              Ninety-Four Thousand Seven Hundred Seventy-One (94,771) shares
              (the "Unit Shares") are to be issued by the Company to certain
              holders (the "Selling Shareholders") of units of limited
              partnership interest (the "Units") in AMB Property, L.P., a
              Delaware limited partnership (the "Operating Partnership"), upon
              exchange of such Units, and One Million Four Hundred Sixty-Five
              Thousand Nine Hundred Twenty-Six (1,465,926) shares (the
              "Performance Shares") are to be issued by the Company to certain
              holders (the "Performance Shareholders") of performance units of
              limited partnership interest (the "Performance Units") in the
              Operating Partnership upon exchange of such Performance Units
              ------------------------------------------------------------------

Ladies and Gentlemen:

              We have acted as special Maryland corporate counsel to the Company
in connection with the registration of the Shares under the Securities Act of
1933, as amended (the "Act"), on Form S-3, filed or to be filed with the
Securities and Exchange Commission (the "Commission") on or about November 19,
2001, and any amendments thereto, if any are to be filed with the Commission
subsequent to the date hereof. You have requested our opinion with respect to
the matters set forth below.

              In our capacity as special Maryland corporate counsel to the
Company and for the purposes of this opinion, we have examined originals, or
copies certified or otherwise identified to our satisfaction, of the following
documents (collectively, the "Documents"):

              (i)    the corporate charter of the Company (the "Charter"),
                     represented by Articles of Incorporation filed with the
                     Maryland State Department of Assessments and Taxation (the
                     "Department") on November 24, 1997, Articles of Merger
                     filed with the Department on November 24, 1997, Articles of
                     Merger filed with the Department on November 26, 1997,
                     Articles Supplementary filed with the Department on July
                     23, 1998 (the "July 1998 Articles Supplementary"), Articles
                     Supplementary filed with


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BALLARD SPAHR ANDREWS & INGERSOLL, LLP

AMB Property Corporation
November 19, 2001
Page 2

                     the Department on November 12, 1998, Articles Supplementary
                     filed with the Department on November 25, 1998, Certificate
                     of Correction filed with the Department on March 18, 1999,
                     correcting the July 1998 Articles Supplementary, Articles
                     Supplementary filed with the Department on May 5, 1999,
                     Articles Supplementary filed with the Department on August
                     31, 1999, Articles Supplementary filed with the Department
                     on March 23, 2000, Articles Supplementary filed with the
                     Department on August 30, 2000, Articles Supplementary filed
                     with the Department on September 1, 2000, Articles
                     Supplementary filed with the Department on March 21, 2001
                     and Articles Supplementary filed with the Department on
                     September 24, 2001;

              (ii)   the Bylaws of the Company, as adopted on November 24, 1997
                     and as amended and restated pursuant to the First Amended
                     and Restated Bylaws of the Company, on or as of March 5,
                     1999, and as further amended and restated pursuant to the
                     Second Amended and Restated Bylaws of the Company, on or as
                     of February 27, 2001 (the "Bylaws");

              (iii)  the Written Organizational Action of the Board of Directors
                     of the Company, dated as of November 24, 1997 (the
                     "Organizational Minutes");

              (iv)   resolutions adopted by the Board of Directors of the
                     Company, or the Executive Committee thereof, on or as of
                     June 19, 1998, November 18, 1998, December 4, 1998,
                     December 10, 1999 and November 16, 2001, which, among other
                     things, authorized the issuance of the Unit Shares and the
                     Performance Shares (collectively, the "Directors'
                     Resolutions");

              (v)    the Fifth Amended and Restated Agreement of Limited
                     Partnership of the Operating Partnership, dated as of
                     September 21, 2001 (the "Operating Partnership Agreement");

              (vi)   a certificate of W. Blake Baird, President of the Company,
                     and Tamra D. Browne, Vice President, General Counsel and
                     Secretary of the Company, dated as of November 19, 2001
                     (the "Officers' Certificate"), to the effect that, among
                     other things, the Charter, the Bylaws, the Organizational
                     Minutes, the Directors' Resolutions and the Partnership
                     Agreement are true, correct and complete, and that the
                     Charter and the Bylaws have not been rescinded or modified
                     and are in full force and effect as of the date of the
                     Officers' Certificate;


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BALLARD SPAHR ANDREWS & INGERSOLL, LLP

AMB Property Corporation
November 19, 2001
Page 3

              (vii)  the Registration Statement on Form S-3 and the related form
                     of prospectus included therein, in substantially the form
                     filed or to be filed with the Commission pursuant to the
                     Act (the "Registration Statement");

              (viii) a status certificate of the Department, dated November 6,
                     2001, to the effect that the Company is duly incorporated
                     and existing under the laws of the State of Maryland; and

              (ix)   such other laws, records, documents, certificates, opinions
                     and instruments as we have deemed necessary to render this
                     opinion, subject to the limitations, assumptions and
                     qualifications noted below.

              In reaching the opinion set forth below, we have assumed the
following:

              (a)    each person executing any of the Documents on behalf of a
                     party (other than the Company) is duly authorized to do so;

              (b)    each natural person executing any of the Documents is
                     legally competent to do so;

              (c)    any of the Documents submitted to us as originals are
                     authentic; the form and content of any Documents submitted
                     to us as unexecuted drafts do not differ in any respect
                     relevant to this opinion from the form and content of such
                     documents as executed and delivered; any of the Documents
                     submitted to us as certified or photostatic copies conform
                     to the original documents; all signatures on all of the
                     Documents are genuine; all public records reviewed or
                     relied upon by us or on our behalf are true and complete;
                     all statements and information contained in the Documents
                     are true and complete; there has been no modification of,
                     or amendment to, any of the Documents, and there has been
                     no waiver of any provision of any of the Documents by
                     action or omission of the parties or otherwise; and

              (d)    the Units and the Performance Units have been and are duly
                     authorized and validly issued by the Operating Partnership,
                     and none of the Unit Shares or the Performance Shares will
                     be issued or transferred in violation of the provisions of
                     Article IV, Section E of the Charter relating to
                     restrictions on ownership and transfer of stock.


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BALLARD SPAHR ANDREWS & INGERSOLL, LLP

AMB Property Corporation
November 19, 2001
Page 4

              Based on the foregoing, and subject to the assumptions and
qualifications set forth herein, it is our opinion that, as of the date of this
letter:

              1)     The Company is a corporation duly incorporated and validly
                     existing as a corporation in good standing under the laws
                     of the State of Maryland.

              2)     The issuance of the Shares has been duly authorized by all
                     necessary corporate action on the part of the Company and
                     when such Shares are issued and delivered by the Company to
                     the Selling Shareholders or the Performance Shareholders,
                     as applicable, in exchange for the Units or Performance
                     Units, as the case may be, in each case upon and subject to
                     the terms set forth in the Operating Partnership Agreement
                     and the Directors' Resolutions, such shares will be validly
                     issued, fully paid and non-assessable.

              The foregoing opinion is limited to the substantive laws of the
State of Maryland, and we do not express any opinion herein concerning any other
law. We express no opinion as to the applicability or effect of any federal or
state securities laws, including the securities laws of the State of Maryland,
or as to federal or state laws regarding fraudulent transfers. To the extent
that any matter as to which our opinion is expressed herein would be governed by
any jurisdiction other than the State of Maryland, we do not express any opinion
on such matter.

              This opinion letter is issued as of the date hereof and is
necessarily limited to laws now in effect and facts and circumstances presently
existing and brought to our attention. We assume no obligation to supplement
this opinion letter if any applicable laws change after the date hereof, or if
we become aware of any facts or circumstances that now exist or that occur or
arise in the future and may change the opinions expressed herein after the date
hereof.

              We consent to your filing this opinion as an exhibit to the
Registration Statement and further consent to the filing of this opinion as an
exhibit to the applications to securities commissioners for the various states
of the United States for registration of the Unit Shares and the Performance
Shares. We also consent to the identification of our firm as Maryland counsel to
the Company in the section of the Registration Statement entitled "Legal
Matters." In giving this consent, we do not admit that we are within the
category of persons whose consent is required by Section 7 of the Act.

                                      Very truly yours,

                                      /s/ Ballard Spahr Andrews & Ingersoll, LLP


