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             [Letterhead of Ballard Spahr Andrews & Ingersoll, LLP]

                                                                     EXHIBIT 5.1


                                 April 9, 1999



AMB Property Corporation
505 Montgomery Street
San Francisco, California 94111

        Re:     Registration Statement on Form S-3

Ladies and Gentlemen:

        We have served as Maryland counsel to AMB Property Corporation, a
Maryland corporation (the "Company"), in connection with the registration with
the Securities and Exchange Commission (the "Commission") of up to 699,837
shares of common stock, par value $.01 per share (the "Shares"), of the Company
covered by the Registration Statement (as defined herein). The Shares are to be
issued by the Company upon the exchange of units of limited partnership interest
(the "Units") of AMB Property, L.P., a Delaware limited partnership (the
"Partnership"), of which the Company is general partner, in accordance with the
Agreement of Limited Partnership of AMB Property, L.P., as amended to date (the
"Partnership Agreement").

        In connection with our representation of the Company, and as a basis for
the opinion hereinafter set forth, we have examined originals, or copies
certified or otherwise identified to our satisfaction, of the following
documents (collectively, the "Documents"):

        1.      The Registration Statement on Form S-3 (the "Registration
Statement"), in substantially the form filed or to be filed by the Company with
the Commission under the Securities Act of 1933, as amended (the "1933 Act"),
and the related form of prospectus, pursuant to which the Shares are to be
issued;

        2.      The charter of the Company (the "Charter");

        3.      The Bylaws of the Company, certified as of a recent date by an
officer of the Company;

        4.      Resolutions adopted by the Board of Directors of the Company on
or as of June 19, 1998 and November 18, 1998, authorizing, among other things,
the Corporation, on its own behalf and on behalf of the Partnership, as its
general partner, to cause the Partnership to issue the Units, to issue the
Shares in exchange for the Units, and to file the Registration Statement;


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AMB Property Corporation
April 9, 1999
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        5.      A certificate as of a recent date of the SDAT as to the good
standing of the Company;

        6.      The form of certificate evidencing a Share, certified as of a
recent date by an officer of the Company;

        7.      The Partnership Agreement;

        8.      A certificate executed by an officer of the Company, dated as of
a recent date; and

        9.      Such other documents and matters as we have deemed necessary or
appropriate to express the opinion set forth in this letter, subject to the
assumptions, limitations and qualifications stated herein.

        In expressing the opinion set forth below, we have assumed, and so far
as is known to us there are no facts inconsistent with, the following:

        1.      Each individual executing any of the Documents, whether on
behalf of such individual or another person, is legally competent to do so.

        2.      Each individual executing any of the Documents on behalf of a
party (other than the Company) is duly authorized to do so.

        3.      Each of the parties (other than the Company) executing any of
the Documents has duly and validly executed and delivered each of the Documents
to which such party is a signatory, and such party's obligations set forth
therein are legal, valid and binding and are enforceable in accordance with all
stated terms.

        4.      Any 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 Documents submitted to us as certified
or photostatic copies conform to the original documents. All signatures on all
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.


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AMB Property Corporation
April 9, 1999
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        5.     The Units have been and are validly issued units of limited
partnership interest in the Partnership, and the Units are not and have not
been, nor are or will the Shares be, issued in violation of any restriction or
limitation contained in the Charter.

        The phrase "known to us" is limited to the actual knowledge, without
independent inquiry, of the lawyers at our firm who have performed legal
services in connection with the issuance of this opinion.

        Based upon the foregoing, and subject to the assumptions, limitations
and qualifications stated herein, it is our opinion that:

        1.      The Company is a corporation duly formed and existing under and
by virtue of the laws of the State of Maryland and is in good standing with the
SDAT.

        2.      The Shares have been duly authorized for issuance and, when and
if issued and delivered against tender of the Units for exchange in accordance
with the Partnership Agreement and the Resolutions, will be validly issued,
fully paid and nonassessable.

        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.

        We assume no obligation to supplement this opinion if any applicable law
changes after the date hereof or if we become aware of any fact that might
change the opinion expressed herein after the date hereof.

        This opinion is being furnished to you for submission to the Commission
as an exhibit to the Registration Statement. We consent to the filing of this
opinion as an exhibit to the Registration Statement and to the use of the name
of our firm in the section entitled "Legal Matters" in the Registration
Statement. 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 1933 Act.

                                   Very truly yours,


                                   /s/ Ballard Spahr Andrews & Ingersoll, LLP
