Exhibit 23.1



                         CONSENT OF INDEPENDENT ACCOUNTANTS

As independent public accountants, we hereby consent to the incorporation of 
our report dated January 23, 1998 in this Form 8-K on the combined statement 
of revenue and certain expenses of Three 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.,
  February 23, 1998