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                                                                   EXHIBIT 10.20

                                    GUARANTEE

      THIS GUARANTEE is entered into as of the 30th day of September, 2003 and
is made by the undersigned (the "Guarantor") in favor of Brookdale Senior
Housing, LLC, a Delaware limited liability company ("Buyer").

      WHEREAS, pursuant to that certain Real Estate Purchase Agreement dated as
of September 19, 2003 (the "Agreement") between AH PENNSYLVANIA OWNER LIMITED
PARTNERSHIP, an Ohio limited partnership, (the "Seller"), as seller, and the
Buyer, as buyer in which Buyer did agree to buy and Seller did agree to sell
that certain property located at 1050 McNeilly Road in the City of Mount
Lebanon, County of Allegheny, State of Pennsylvania (the "Property"); and

      WHEREAS, in order to induce Buyer to enter into the Agreement, the
Guarantor has agreed to guarantee the performance of Seller's obligations under
the Agreement.

      NOW THEREFORE, in consideration of the foregoing, and of the terms and
provisions set forth below, and other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, the parties do hereby
agree as follows:

      1. Guarantor hereby, unconditionally and irrevocably, guarantees to Buyer
and its respective members the full, prompt and faithful performance of Seller's
Obligations. If Seller shall become the debtor under the Federal Bankruptcy Code
or the subject of any other state or federal bankruptcy, insolvency or similar
proceeding, the same shall not affect the liability of any Guarantor hereunder.

      2. Upon the failure of Seller to meet Seller's obligations, Guarantor
shall, within five (5) business days from the date notice of such failure is
given to Guarantor, cure such failure. If any such failure to perform shall not
be cured by Guarantor within said five (5) business day period, Buyer may, at
its option, cure such all failures to perform Seller's obligations, including
the payment of any and all costs outstanding which were part of Seller's
obligations.

      3. Guarantor hereby waives absolutely and irrevocably any right of
subrogation to Buyer's claims against Seller and any right of indemnity,
reimbursement or contribution from Seller with respect to any payment made or
performance undertaken by Guarantor pursuant hereto.

      4. Without limiting or lessening the liability of the Guarantor under this
Guarantee, Buyer may, without notice to the Guarantor,

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      (a)   grant extensions of time or any other indulgences on Seller's
            obligations; and

      (b)   accept or make other arrangements with Seller and otherwise deal
            with Seller or other parties as Buyer may deem expedient.

      5. This Guarantee shall be a continuing guarantee, shall not be revoked by
death, shall inure to the benefit of, and be enforceable by, any successor or
assign of Buyer and shall be binding upon, and enforceable against, the
Guarantor and its successors and assigns.

      6. Except as expressly provided herein or in the Agreement, all additional
demands, presentments, notices of protest and dishonor, and notices of every
kind and nature, including those of any action or no action on the part of
Seller or Buyer are expressly waived by Guarantor. This is a guarantee of
payment and not of collection. Except as expressly provided herein or in the
Agreement, Guarantor hereby waives the right to require Buyer to proceed against
Seller or any other party and waives the right to require Buyer to pursue any
other remedy for the benefit of the Guarantor.

      7. Guarantor agrees to pay reasonable attorneys' fees and all other
reasonable costs and expenses which may be incurred in the enforcement of this
Guarantee after the failure of Guarantor to cure within the five (5) business
day time period as provided in paragraph 2 above.

      8. Any notice or demand hereunder shall be in writing, may be delivered
personally or sent by certified mail with postage prepaid or by reputable
courier service with charges prepaid, or, if to Buyer, by telecopier whereby the
receipt thereof may be confirmed. Any notice sent to the Guarantor shall be
addressed to the Guarantor at the address set forth below or such other address
in the United States of America as the Guarantor shall designate in a notice
given to Buyer in the manner described herein. Any notice sent to Buyer shall be
addressed to the attention of the Real Estate Investment Department at 720 East
Wisconsin Avenue, Milwaukee, WI 53202 and shall refer to NML JV No. 333313 and,
if telecopied, shall be telecopied to 414/665-1557, or at such other address or
telecopier number as Buyer shall designate in a notice given in the manner
described herein. Any notice or demand sent hereunder by telecopier shall also
be sent by regular U.S. mail, certified mail or reputable courier service. Any
notice or demand hereunder shall be deemed given when received. Any notice or
demand which is rejected, the acceptance of delivery of which is refused or
which is incapable of being delivered on a business day for any cause occasioned
by the addressee at the address or telecopier number specified herein or such
other address or telecopier number as may be designated pursuant hereto shall be
deemed received as of the date of attempted delivery.

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Mailing Addresses:

Brookdale Living Communities, Inc.
330 North Wabash Avenue, Suite 1400
Chicago, IL 60611

         GUARANTOR: AH PENNSYLVANIA OWNER LIMITED
                    PARTNERSHIP, an Ohio limited partnership

                    By: AH PENNSYLVANIA CGP, INC.,
                        an Ohio corporation, its general partner

                        By: /s/ R. Stanley Young
                            ----------------------------------
                        Name: R. Stanley Young
                        Its: Vice President

                    By: AH PENNSYLVANIA SUBORDINATED, LLC, an
                        Ohio limited liability company, its limited partner

                        By: /s/ R. Stanley Young
                            ----------------------------------
                        Name: R. Stanley Young
                        Its: Vice President