<PAGE>

                                                                    Exhibit 10.2
 
                             The Prime Group, Inc.
                             77 West Wacker Drive
                                  Suite 3900
                            Chicago, Illinois 60601


                                  May 7, 1997


Mr. Mark J. Schulte
Brookdale Living Communities, Inc.
77 West Wacker Drive
Suite 3900
Chicago, Illinois 60601

          Re:  Space Sharing Agreement
               -----------------------
Dear Mark:

          This letter agreement shall set forth the terms upon which the
undersigned ("PGI") agrees to provide to Brookdale Living Communities, Inc.
("Brookdale") the use of certain space and facilities located within PGI's
leased premises ("Premises") on the 39th floor of the building known as 77 West
Wacker Drive following the completion of the initial public offering of stock in
Brookdale (the "Offering").

          The space and facilities which Brookdale will be permitted to use are
those portions of the Premises and facilities therein which are being used on
the date hereof by persons who are, or after the Offering will become, officers
or employees of Brookdale. If Brookdale uses more space and facilities than
contemplated by the immediately preceding sentence, the rent payable by
Brookdale pursuant to this agreement shall be adjusted appropriately. Such use
shall conform with the nature and extent of the existing use of the space and
facilities which are the subject hereof.

          The term of this agreement shall commence on the date of the Offering
and shall end on the last day of the fourth (4th) full calendar month
thereafter; provided, however, that Brookdale shall have the right to extend the
term of this agreement in increments of two (2) months or more for a total of up
to twelve (12) additional months so long as (i) Brookdale has given PGI written
notice of any such extension not later than the last day of the month preceding
the date on which the term (as previously extended, if applicable) would
otherwise expire and (ii) Brookdale is not in default of any obligation under
this agreement as of the date of any such notice or the commencement of the
applicable extension.

          Brookdale shall pay as monthly rent for the space and facilities
described herein an amount equal to the sum of (i) Eight Thousand Eight Hundred
and no/100 Dollars ($8,800.00) plus (ii) a
<PAGE>

Mr. Mark J. Schulte
May 7, 1997
Page 2

 
fair and equitable percentage of the taxes and operating expenses for the
Premises. Such rent shall be paid monthly, in advance, on the first day of the
term and on the first day of each calendar month thereafter, except that if the
first day of the term shall be a day other than the first day of a calendar
month, rent for such month shall be prorated based on the number of days in such
month.

          In addition, Brookdale shall be responsible for the incremental cost
to PGI of any utilities and services used by Brookdale during the term of this
agreement, as reasonably determined by PGI, including, without limitation, the
cost of copying and facsimile equipment. All amounts owing to PGI under this
paragraph shall be paid by Brookdale within ten (10) days after receipt of an
invoice therefor.

          Brookdale acknowledges that it has received and reviewed a copy of the
lease dated March 14, 1992, as amended on April 15, 1992, with respect to the
Premises and agrees that Brookdale's use of the space and facilities described
herein shall be subject to the terms and provisions of such lease and that
Brookdale shall comply with all of the terms and provisions of such lease to the
extent such terms and provisions relate to or affect Brookdale's use of the
space and facilities described herein.

                                    Sincerely,

                                    THE PRIME GROUP, INC.


                                    By:  /s/ Richard S. Curto
                                         ---------------------------
                                    Name:  Richard S. Curto
                                         ---------------------------
                                    Title: Executive Vice President
                                           -------------------------

ACCEPTED AND AGREED TO BY:

BROOKDALE LIVING COMMUNITIES, INC.


By:   /s/ Mark J. Schulte
      -------------------------
Name:  Mark J. Schulte 
      -------------------------
Title: President
      -------------------------


Dated:  May 7, 1997
 
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                              LANDLORD'S CONSENT
                              ------------------


          The undersigned, being the landlord of the building known as 77 West
Wacker Drive, Chicago, Illinois, does hereby consent to the foregoing letter
agreement between The Prime Group, Inc. and Brookdale Living Communities, Inc.

                                 77 WEST WACKER LIMITED PARTNERSHIP

                                 By:  The Prime Group, Inc., managing
                                      general partner


                                      By:    /s/ Richard S. Curto
                                         ---------------------------- 
                                      Name:  Richard S. Curto
                                           -------------------------- 
                                      Title: Executive Vice President
                                            ------------------------- 

                                      Dated: May 7, 1997