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                                  [LETTERHEAD]





                                 August 11, 2000



The Board of Trustees
ProLogis Trust
14100 East 35th Place
Aurora, Colorado 80011

Re:      ProLogis Trust Registration Statement on Form S-3


Ladies and Gentlemen:

         We have acted as special counsel to ProLogis Trust, a Maryland real
estate investment trust ("ProLogis"), in connection with the registration of
401,071 common shares of beneficial interest, par value $0.01 per share, of
ProLogis (the "Common Shares"), as described in the Registration Statement filed
on the date hereof on Form S-3 with the Securities and Exchange Commission under
the Securities Act of 1933, as amended, (together with all amendments thereto,
the "Registration Statement").

         As special counsel to ProLogis, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of ProLogis' declaration
of trust and bylaws, the resolutions of ProLogis' Board of Trustees and such of
ProLogis' records, certificates and other documents and such questions of law as
we considered necessary or appropriate for the purpose of this opinion. As to
certain facts material to our opinion, we have relied, to the extent we deem
such reliance proper, upon certificates of public officials and officers of
ProLogis. In rendering this opinion, we have assumed the genuineness of all
signatures, the authenticity of all documents submitted to us as originals and
the conformity to authentic original documents of all documents submitted to us
as copies.

         Based upon and subject to the foregoing and to the assumptions,
conditions and limitations set forth herein, we are of the opinion that the
Common Shares have been duly authorized and, when the Common Shares are issued
and sold in the manner described in the Registration Statement, will be legally
issued, fully paid and, except as described below, nonassessable.



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Board of Trustees
ProLogis Trust
August 11, 2000
Page 2


         Our opinion relating to the nonassessability of the Preferred Shares
and the Common Shares does not pertain to the potential liability of
shareholders of ProLogis for debts and liabilities of ProLogis. Section 5-419(a)
of the Maryland Courts and Judicial Proceedings Code provides that "a
shareholder ... of a real estate investment [trust] ... is not personally
liable for the obligations of the real estate investment trust." The Declaration
of Trust provides that no shareholder shall be personally or individually liable
in any manner whatsoever for any debt, act, omission or obligation incurred by
ProLogis or ProLogis' Board of Trustees. The Declaration of Trust further
provides that ProLogis shall indemnify and hold harmless shareholders against
all claims and liabilities and related reasonable expenses to which they become
subject by virtue of their status as current or former shareholders. In
addition, we have been advised that ProLogis, as a matter of practice, inserts a
clause in its business, management and other contracts that provides that
shareholders shall not be personally liable thereunder. Accordingly, no personal
liability should attach to ProLogis' shareholders for contract claims under any
contract containing such a clause where adequate notice is given. However, with
respect to tort claims, contract claims where shareholder liability is not so
negated, claims for taxes and certain statutory liability, the shareholders may,
in some jurisdictions, including Colorado, the state in which ProLogis'
principal executive office is located, be personally liable for such claims and
liabilities.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to all references to our firm in the Registration
Statement.

         The opinions contained herein are limited to Federal laws of the United
States, the laws of the State of Illinois and the laws of the State of Maryland
governing real estate investment trusts. We are not purporting to opine on any
matter to the extent that it involves the laws of any other jurisdiction.

         These opinions are furnished to you solely for your benefit in
connection with the transactions described herein and are not to be used for any
other purpose without our prior written consent.


                                       Very truly yours,



                                       /s/ MAYER, BROWN & PLATT