JOINT FILING AGREEMENT

                                   
                                   EXHIBIT 4

                            JOINT FILING AGREEMENT

     In accordance with Rule 13d-1(k) of the Securities Exchange Act of 1934,
as amended, the undersigned hereby agree to the joint filing on behalf of
each of us of a statement on Schedule 13D relating to the Common Stock, par
value $.01 per share, of Berkshire Realty Company, Inc., a Delaware
corporation, and that any amendments thereto filed by any of us will be filed
on behalf of each of us.  This agreement may be included as an exhibit to
such joint filing.

                                       BLACKSTONE REAL ESTATE ACQUISITIONS
                                       III L.L.C.

                                       By:/s/  Xxxx Xxxxxx
                                          ______________________________
                                          Name:  Xxxx Xxxxxx
                                          Title: Vice President

                                       BLACKSTONE REAL ESTATE ADVISORS III,
                                       L.P.

                                       By:  BRE ADVISORS III L.L.C.


                                       By:/s/ Xxxx Xxxxxx
                                          ______________________________
                                          Name:  Xxxx Xxxxxx  
                                          Title: Vice President

                                       BRE ADVISORS III L.L.C.


                                       By:/s/  Xxxx Xxxxxx
                                          ______________________________
                                          Name:  Xxxx Xxxxxx
                                          Title: Vice President



                                       /s/  Xxxx Xxxxxx
                                       _________________________________
                                       XXXXX X. XXXXXXXX

                                       By:  Xxxx Xxxxxx, Attorney-in-Fact

                                       /s/  Xxxx Xxxxxx
                                       _________________________________
                                       XXXXXXX X. XXXXXXXXXX

                                       By:  Xxxx Xxxxxx, Attorney-in-Fact



Dated: March 3, 1999