EXHIBIT 4.12
                               SNH CAPITAL TRUST I

                              CERTIFICATE OF TRUST


         THIS IS TO CERTIFY THAT:

         FIRST:  The undersigned  trustees hereby form a business trust pursuant
to the laws of the State of Maryland.

         SECOND: The name of the business trust (the "Trust") is:

                               SNH Capital Trust I

         THIRD:  The  address of the  Trust's  principal  office in the State of
Maryland is c/o Ballard Spahr Andrews & Ingersoll, LLP, 300 East Lombard Street,
Baltimore, Maryland 21202, Attention: James J. Hanks, Jr.

         FOURTH: The name and business address of the Trust's resident agent are
James J. Hanks,  Jr.,  c/o Ballard  Spahr  Andrews &  Ingersoll,  LLP,  300 East
Lombard Street, Baltimore, Maryland 21202.

         The undersigned, being all of the trustees of the Trust, acknowledge
under the penalties of perjury, that to the best of their knowledge and belief,
the facts stated herein are true.

         IN WITNESS WHEREOF, each of the undersigned trustees have signed this
Certificate of Trust this 4th day of May, 2001.


                                            /s/ Gerard M. Martin
                                            Gerard M. Martin


                                            /s/ Barry M. Portnoy
                                            Barry M. Portnoy