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Exhibit 23.1



                       CONSENT OF INDEPENDENT ACCOUNTANTS

As independent public accountants, we hereby consent to the incorporation of our
report dated April 27, 1998 in this Form 8-K on the combined statement of
revenue and certain expenses of the First Commercial Properties and our report
dated May 1, 1998 in this Form 8-K on the statement of revenue and certain 
expenses of One Christina Centre into the Company's previously filed 
Registration Statements on Forms S-3 (File No. 333-46647, File No. 333-39155 and
File No. 333-20999) and Forms S-8 (File No. 333-14243 and File No. 333-28427).

                                                     ARTHUR ANDERSEN LLP

Philadelphia, Pa.,
     May 13, 1998

