EXHIBIT 5.1




                            September 27, 2001


ProLogis Trust
14100 East 35th Place
Aurora, Colorado  80011

         Re:    Registration Statement on Form S-8 Employee Share Purchase Plan

Ladies and Gentlemen:

         We have acted as counsel to ProLogis Trust, a Maryland real estate
investment trust ("ProLogis"), in connection with the proceedings (the
"Proceedings") taken and to be taken relating to the registration by
ProLogis of an aggregate of 5,000,000 common shares of beneficial interest,
$.01 par value per share (the "Shares"), with the Securities and Exchange
Commission (the "SEC") in connection with ProLogis's Employee Share
Purchase Plan (the "Plan"). We have also participated in the preparation
and filing with the SEC under the Securities Act of 1933, as amended, of a
registration statement on Form S-8 (the "Registration Statement") relating
to the Shares.

         As counsel to ProLogis, we have examined originals or copies
certified to our satisfaction of ProLogis's Amended and Restated
Declaration of Trust and Bylaws, resolution of the Board of Trustees and
such other ProLogis records, instruments, certificates and documents and
such questions of law as we considered necessary or appropriate to enable
us to express 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 photostatic copies.

         Based upon and subject to the foregoing and to the assumptions,
limitations and conditions set forth herein, we are of the opinion that,
upon completion of the Proceedings, the Shares will have been validly
issued and delivered in accordance with the Proceedings and the Plan, the
Shares will be validly issued, fully paid and nonassessable.

         We hereby consent to the filing of this opinion as an exhibit to
the Registration Statement.

                                                     Very truly yours,

                                                     /s/ Mayer, Brown & Platt

                                                     MAYER, BROWN & PLATT