Document:

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                                                                 Exhibit 10.5(b)

                    SONESTA INTERNATIONAL HOTELS CORPORATION
                                (the "Borrower")

             Fourth Allonge to $2,000,000 Commercial Promissory Note
                      dated September 29, 2000 (the "Note")

                                                           Boston, Massachusetts
                                                           January 30, 2004

         1.    Amendment to Maturity.

         As used in the Note, the definition of "Maturity" is hereby amended to
read "December 31, 2004."

         THIS ALLONGE IS MADE AND DELIVERED by the Borrower and shall be a part
of the Note. The Note referred to above, as amended hereby, is hereby reaffirmed
by the Borrower.

                                       SONESTA INTERNATIONAL
                                       HOTELS CORPORATION

                                       By: /S/
                                           -------------------------------------
                                            Boy A.J. van Riel
                                            Vice President & Treasurer

1309840.2

                                                                              31<Page>

                                                                 Exhibit 10.5(c)

                    SONESTA INTERNATIONAL HOTELS CORPORATION
                                (the "Borrower")

             Third Allonge to $2,000,000 Commercial Promissory Note
                      dated September 29, 2000 (the "Note")

                                                           Boston, Massachusetts
                                                           November 24, 2003

         1.    Amendment to Maturity.

         As used in the Note, the definition of "Maturity" is hereby amended to
read "January 31, 2004."

         THIS ALLONGE IS MADE AND DELIVERED by the Borrower and shall be a part
of the Note. The Note referred to above, as amended hereby, is hereby reaffirmed
by the Company.

                                     SONESTA INTERNATIONAL
                                     HOTELS CORPORATION

                                     By: /S/
                                         ---------------------------------------
                                          Peter J. Sonnabend
                                          Vice Chairman

1309840.2

                                                                              32<Page>

                                                                 Exhibit 10.6(a)

COMMONWEALTH OF MASSACHUSETTS
COUNTY OF MIDDLESEX

Prepared by:
And when recorded mail to:
Otten, Johnson, Robinson,
  Neff & Ragonetti, P.C.
950 Seventeenth Street
Suite 1600
Denver, Colorado 80202
Attention:  David T. Brennan, Esq.

                    MORTGAGE AND LOAN MODIFICATION AGREEMENT

          This MORTGAGE AND LOAN MODIFICATION AGREEMENT (this "Agreement"),
dated as of March 24, 2004, to be effective as of December 1, 2003 (the
"Effective Date"), is made by and between ROGER P. SONNABEND, PETER J. SONNABEND
and BOY A.J. VAN RIEL, trustees of the Charterhouse of Cambridge Trust, and not
individually, under a Declaration of Trust dated December 27, 1963 and recorded
at Middlesex South Deeds Book 11160, Page 340, as amended by an Amendment of
Declaration of Trust dated July 8, 1966 and recorded at Middlesex South Deeds
Book 11160, Page 359 ("Charterhouse"), and SONESTA OF MASSACHUSETTS, INC., a
Massachusetts corporation ("Sonesta" and, together with Charterhouse,
"Borrower"), and SUNAMERICA LIFE INSURANCE COMPANY, an Arizona corporation
("Lender").

                                    RECITALS

          A.    On or about December 18, 1996, Lender made a loan in the
principal amount of $22,880,000.00 (the "Original Loan") to Borrower.

          B.    The Original Loan was evidenced by a Promissory Note dated
December 18, 1996, in the original principal amount of the Original Loan
executed by Borrower to the order of Lender (the "Original Note"), and is
secured by, among other things, a Mortgage, Security Agreement, Fixture Filing,
Financing Statement and Assignment of Leases and Rents dated as of December 18,
1996 (the "Original Mortgage"), executed by Borrower for the benefit of Lender,
encumbering certain real property and improvements thereon commonly known as the
Royal Sonesta Hotel, City of Cambridge, County of Middlesex, Massachusetts, and
more particularly described in the Original Mortgage and in EXHIBIT A attached
hereto (the "Property"). The Original Mortgage was recorded on July 3, 1997, at
Book 26983, Page 631, in the Middlesex South District Registry of Deeds (the
"Records").

                                                                              33
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          C.    In connection with the Original Loan, Borrower executed a
Replacement Reserve and Security Agreement dated as of December 18, 1996 (the
"Replacement Reserve and Security Agreement") for the benefit of Lender.

          D.    On or about June 2, 2000, Lender made an additional advance of
$19,865,733.66 (the "Additional Advance") on the Original Loan. The Original
Loan and the Additional Advance were consolidated and are evidenced by an
Amended and Restated Promissory Note dated May 30, 2000, in the original
principal amount of $41,000,000.00, executed by Borrower to the order of Lender
(the "Note"). In connection with the Additional Advance, Borrower and Lender
executed a Mortgage and Loan Modification Agreement dated as of May 30, 2000
(the "Modification Agreement"). The Modification Agreement was recorded at Book
31470, Page 360, in the Records.

          E.    The Original Loan and the Additional Advance, as consolidated
and evidenced by the Note, and as secured by the Original Mortgage as modified
by the Modification Agreement, are referred to collectively herein as the
"Loan." The Original Mortgage, as modified by the Modification Agreement, is
referred to herein as the "Mortgage." The Original Note, the Original Mortgage,
the Replacement Reserve and Security Agreement and each other document executed
by Borrower and evidencing or securing the Original Loan, together with the
Note, the Modification Agreement and each other document executed by Borrower in
connection with the Additional Advance, are referred to herein, collectively, as
the "Loan Documents."

          F.    As of the Effective Date, the outstanding principal balance
existing under the Loan is $39,346,801.84 and there is no accrued and unpaid
interest due thereon.

          G.    Borrower and Lender wish to provide modified repayment terms for
the Loan, and wish to modify certain terms of the Note, the Mortgage and the
other Loan Documents to reflect certain other agreements as hereinafter
provided.

                                    AGREEMENT

          NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Borrower and Lender hereby agree
as follows:

          1.    NO DEFENSES, SETOFFS OR COUNTERCLAIMS. The Lender has performed
all of its obligations to date under the Loan Documents, and the amounts owed by
the Borrower to the Lender under the Loan are free from any defenses, setoffs or
counterclaims in favor of the Borrower against the Lender. To the extent that
any such defenses, setoffs, or counterclaims now exist, Borrower hereby waives
and releases the same in exchange for the Lender's agreement to modify the Loan
and the Loan Documents as set forth herein.

          2.    MODIFICATION OF NOTE.

                (a)  Section 1 of the Note is hereby modified to provide that:

                     (i)   The balance of principal outstanding from time to
     time under the Note shall continue to bear interest at eight and sixty
     one-hundredths percent

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     (8.60%, hereinafter the "Note Rate"), based on a 360-day year for the
     actual number of days elapsed.

                     (ii)  Commencing on January 1, 2004, and on the first day
     of each month thereafter through and including December 1, 2006 (the
     "Reduced Payment Period"), provided that no Event of Default has occurred
     under the Note or any of the other Loan Documents, payments of interest
     only on the principal balance of the Note, at the rate of five percent
     (5.00%) per annum based on a 360-day year for the actual number of days
     elapsed (the "Reduced Payment Rate"), shall be payable, in arrears. Unpaid
     accrued interest on the Note shall be added to the principal balance of the
     Note on December 1, 2004, December 1, 2005 and December 1, 2006. Maker may
     pay any accrued but unpaid interest on the Note which has been added to the
     principal balance of the Note, without prepayment premium, at any time and
     from time to time, on or before December 31, 2007, as provided in Section
     4.24 of the Mortgage.

                     (iii) Commencing on January 1, 2007, and on the first day
     of each month thereafter through and including December 1, 2007 (the
     "Interest Only Payment Period"), provided that no Event of Default has
     occurred under the Note or any of the other Loan Documents, payments of
     interest only on the principal balance of the Note, at the Note Rate, based
     on a 360-day year for the actual number of days elapsed, shall be payable,
     in arrears.

                     (iv)  Commencing on January 1, 2008, and on the first day
     of each month thereafter through and including June 1, 2010 (the "Principal
     and Interest Payment Period"), combined payments of principal and interest
     shall be payable, in arrears, in the amount of $332,910.63.

                     (v)   The entire outstanding principal balance of the Note,
     together with all accrued and unpaid interest and all other sums due
     thereunder, shall be due and payable in full on July 1, 2010 (the "Original
     Maturity Date").

                (b)  Section 5  of the  Note  is  hereby  modified  to  provide
that if Maker delivers a Defeasance Notice to Holder during the Reduced Payment
Period or the Interest Only Payment Period:

                     (i)   Unpaid accrued interest on the Note shall be added to
     the principal balance of the Note on the Defeasance Date; and

                     (ii)  Maker shall then satisfy the Defeasance Requirements,
     including the remittance of the Defeasance Deposit, such that the
     Defeasance Collateral will be sufficient to pay as and when due the
     principal of and interest on the Note on each regularly scheduled payment
     date thereunder and on the Original Maturity Date, at the Note Rate and on
     the payment schedule set forth in the Note, and not as modified by Section
     2(a) of this Agreement.

                (c)  The third  sentence  of  Section 18  of the Note is hereby
deleted in its entirety and replaced with the following:

                                                                              35
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          The agreement contained in this paragraph to limit the personal
          liability of Maker shall become null and void and be of no further
          force and effect in the event (i) that the Property or any part
          thereof or any interest therein, or any interest in Maker, shall be
          further encumbered by a voluntary lien securing any obligation upon
          which Maker or any general partner, principal or affiliate of Maker
          shall be personally liable for repayment, whether as obligor or
          guarantor which has not been approved in advance by Holder; (ii) of
          any breach or violation of Section 4.24 or 4.25 of the Mortgage; (iii)
          of any breach or violation of Section 5.4, 5.5 or 5.7 of the Mortgage;
          (iv) of any fraud or material misrepresentation by Maker in connection
          with the Property, the Loan Documents or the application made by Maker
          for the Loan; or (v) of any execution, amendment, modification or
          termination without the prior written consent of Holder, if such
          consent is required under the terms of Section 5.3 of the Mortgage, of
          any Primary Lease or Secondary Lease.

          3.    MODIFICATION OF MORTGAGE.

                (a)  Sections 1.4, 1.10, 1.11, 1.12, 1.18, 1.23, 1.26, 1.28,
1.29, 1.30 and 1.32 of the Mortgage are hereby deleted in their entireties, and
the following substituted therefor:

          "1.4  ENVIRONMENTAL INDEMNITY AGREEMENT: The Environmental Indemnity
          Agreement dated as of December 18, 1996 made by Mortgagor and
          Guarantor for the benefit of Mortgagee, as modified by (a) the
          Modification Agreement, (b) the Reaffirmation and Modification of
          Limited Guaranty Agreement and Environmental Indemnity Agreement dated
          as of May 30, 2000 executed by Guarantor for the benefit of Mortgagee,
          (c) the Second Modification Agreement and (d) the Reaffirmation
          Agreement.

          1.10  GUARANTY AGREEMENT: The Limited Guaranty Agreement dated as of
          December 18, 1996 made by Guarantor for the benefit of Mortgagee, as
          modified by (a) the Reaffirmation and Modification of Limited Guaranty
          Agreement and Environmental Indemnity Agreement dated as of May 30,
          2000 executed by Guarantor for the benefit of Mortgagee, and (b) the
          Reaffirmation Agreement.

          1.11  INTANGIBLE PERSONALTY: The right to use all trademarks and
          trade names and symbols or logos used in connection therewith, or any
          modifications or variations thereof, in connection with the operation
          of the improvements existing or to be constructed on the Property,
          together with all accounts, deposit accounts (including, without
          limitation, the Pledged Accounts), letter of credit rights,

                                                                              36
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          monies in the possession of Mortgagee (including without limitation
          proceeds from insurance, retainages, deposits for taxes and insurance
          and monies on deposit in the Additional Collateral Account), Permits,
          contract rights (including, without limitation, rights to receive
          insurance proceeds), amounts paid as rents of the Property or the
          fees, charges, accounts, or other payments for the use or occupancy of
          rooms and other public facilities in the Property, and general
          intangibles (whether now owned or hereafter acquired, and including
          proceeds thereof) relating to or arising from Mortgagor's ownership,
          use, operation, leasing, or sale of all or any part of the Property,
          specifically including but in no way limited to any right which
          Mortgagor may have or acquire to transfer any development rights from
          the Property to other real property, and any development rights which
          may be so transferred.

          1.12  LEASE CERTIFICATE: The Certificate Concerning Secondary Leases
          dated as of March 24, 2004, and effective as of the Effective Date,
          made by Mortgagor to Mortgagee concerning the Secondary Leases.

          1.18  NOTE: Mortgagor's Amended and Restated Promissory Note dated as
          of May 30, 2000, payable to the order of Mortgagee in the principal
          face amount of $41,000,000.00, as modified by the Second Modification
          Agreement, the last payment under which is due on July 1, 2010 or, if
          extended pursuant to its terms, July 1, 2015, unless such due date is
          accelerated, together with all renewals, extensions and modifications
          of such Promissory Note. All terms and provisions of the Note are
          incorporated by this reference in this Mortgage.

          1.23  REPLACEMENT RESERVE AND SECURITY AGREEMENT: The Replacement
          Reserve and Security Agreement dated as of December 18, 1996, executed
          by Mortgagor for the benefit of Mortgagee, as modified by the
          Modification Agreement and Second Modification Agreement.

          1.26  DEFICIENCY GUARANTY AGREEMENT: The Deficiency Guaranty
          Agreement dated as of May 30, 2000, executed by Guarantor for the
          benefit of Mortgagee, as modified by the Reaffirmation and
          Modification of Deficiency Guaranty Agreement dated as of March 24,
          2004, executed by Guarantor for the benefit of Mortgagee.

          1.28  KEY BISCAYNE LOAN DOCUMENTS: The Key Biscayne Note, all of the
          mortgages, deeds of trust, and other instruments and documents
          executed by the Key Biscayne Borrower and/or Guarantor securing the
          Key Biscayne Note, including any guaranty

                                                                              37
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          agreements, environmental indemnity agreements, replacement reserve
          agreements, collateral assignment of liquor licenses, lease
          certificates, and all other documents executed or delivered by the Key
          Biscayne Borrower and/or Guarantor in connection with the transaction
          pursuant to which the Key Biscayne Note has been executed and
          delivered, together with the Key Biscayne Modification Agreement and
          the other documents executed by the Key Biscayne Borrower and/or
          Guarantor in connection with the Key Biscayne Modification Agreement,
          but excluding the Non-Recourse Guaranty Agreement and the Key Biscayne
          Second Mortgage. The term 'Key Biscayne Loan Documents' also includes
          all modifications, extensions, renewals, and replacements of each
          document referred to above.

          1.29  KEY BISCAYNE NOTE: The Consolidated and Renewed Promissory Note
          dated as of May 30, 2000 executed by the Key Biscayne Borrower and
          payable to the order to Mortgagee in the principal face amount of
          $31,000,000.00, as modified by the Key Biscayne Modification
          Agreement, the last payment under which is due on July 1, 2010, or, if
          extended by Mortgagee by its terms, July 1, 2015, unless such due date
          is accelerated, together with all renewals, extensions and
          modifications of such consolidated and renewed promissory note. All
          terms and provisions of the Key Biscayne Note are incorporated by this
          reference in this Mortgage.

          1.30  KEY BISCAYNE SECOND MORTGAGE: The Mortgage, Security Agreement,
          Fixture Filing, Financing Statement and Assignment of Leases and Rents
          dated as of May 30, 2000 executed by Key Biscayne Borrower for the
          benefit of Mortgagee and securing Key Biscayne Borrower's obligations
          under the Non-Recourse Guaranty Agreement, as modified by the Key
          Biscayne Modification Agreement.

          1.32  NON-RECOURSE GUARANTY AGREEMENT: The Non-Recourse Guaranty
          Agreement dated as of May 30, 2000 made by Key Biscayne Borrower for
          the benefit of Mortgagee, and secured by the Key Biscayne Second
          Mortgage, as modified by the Reaffirmation and Modification of
          Non-Recourse Guaranty Agreement dated as of March 24, 2004, executed
          by Key Biscayne Borrower for the benefit of Mortgagee, pursuant to
          which Key Biscayne Borrower has guaranteed payment and performance of
          the Note and the other Loan Documents."

                (b)  The following  definitions  are hereby added to the end of
Article 1 of the Mortgage:

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          "1.33 ADDITIONAL COLLATERAL ACCOUNT: An account maintained by
          Mortgagee or a Servicer designated by Mortgagee, into which Excess
          Cash Flow shall be deposited in accordance with Section 4.24, and
          which shall be additional Collateral for the Loan.

          1.34  ANNUAL CAPITAL EXPENSE AMOUNT: An amount equal to five percent
          (5.00%) of Gross Revenue (as defined in Section 4.24(e)) for the
          Reduced Payment Period and the Interest Only Payment Period (as
          defined in Section 4.24(a)).

          1.35  CAPITAL EXPENSE LIMIT: The Annual Capital Expense Amount plus
          such Annual Capital Expense Amounts accrued in prior years and not
          applied to Capital Expenses of the Property.

          1.36  EFFECTIVE DATE: December 1, 2003.

          1.37  KEY BISCAYNE MODIFICATION AGREEMENT: The Mortgage and Loan
          Modification Agreement dated as of March 24, 2004, executed by Key
          Biscayne Borrower and Mortgagee.

          1.38  PLEDGED ACCOUNTS: The Additional Collateral Account and the
          Pledged Operating Account.

          1.39  PLEDGED OPERATING ACCOUNT: That certain deposit account (ABA #
          011500120; Account # 1110419918) maintained by Mortgagor with Citizens
          Bank.

          1.40  REAFFIRMATION AGREEMENT: The Reaffirmation and Modification of
          Guaranty Agreement and Environmental Indemnity Agreement dated as of
          March 24, 2004, and effective as of the Effective Date, executed by
          Guarantor for the benefit of Mortgagee.

          1.41  SECOND MODIFICATION AGREEMENT: The Mortgage and Loan
          Modification Agreement dated as of March 24, 2004, and effective as of
          the Effective Date, executed by Mortgagor and Mortgagee."

                (c)  Section 4.13 of the Mortgage is hereby modified to provide
that, in addition to the financial reports described therein, Mortgagor must
also provide to Mortgagee, by the twentieth (20th) day of each month during the
Reduced Payment Period and the Interest Only Payment Period (as such terms are
defined in Section 4.24(a)), a report of the Gross Revenue, Operating Expenses,
Net Cash Flow and Excess Cash Flow of the Property for the previous calendar
month (the "Net Cash Flow Report"). The Net Cash Flow Report shall be in such
detail as Mortgagee may require, shall be prepared in accordance with the
Uniform System of Accounts for the Lodging Industry, Ninth Revised Edition,
First Printing 1996 as adopted by the American Hotel and Motel Association, as
amended or supplemented from time to time, and shall be certified as true and
correct by Mortgagor (or, if required by Mortgagee during the

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continuance of any Event of Default, certified by an independent certified
public accountant acceptable to Mortgagee).

                (d)  A new Section 4.24 is hereby added to the Mortgage, as
                     follows:

          "4.24 APPLICATION OF NET CASH FLOW TO CAPITAL EXPENSES; DEFERRED
          INTEREST REDUCTION PAYMENTS; ADDITIONAL COLLATERAL ACCOUNT.

          (a)   For the period from January 1, 2004 through December 31, 2006
          (the "Reduced Payment Period"), and for the period from January 1,
          2007 to December 31, 2007 (the "Interest Only Payment Period"), all
          Net Cash Flow from the Property shall, at Mortgagor's election, either
          be (i) retained in the Pledged Operating Account or transferred by
          Mortgagor to the Central Account as provided in subsection 4.24(b),
          (ii) used to pay Capital Expenses of the Property, subject to
          Mortgagee's prior written approval to the extent that such Capital
          Expenses exceed the Capital Expense Limit, (iii) paid to Mortgagee or
          Servicer for deposit in the Additional Collateral Account, as set
          forth in subsection 4.24(b) hereof, or (iv) paid to Mortgagee (any
          such payment a "Deferred Interest Reduction Payment") and applied (A)
          first, to accrued but unpaid interest on the Loan, and (B) second, to
          accrued but unpaid interest which has been previously added to the
          principal balance of the Loan during the Reduced Payment Period
          ("Capitalized Interest"), without prepayment premium. Except for
          payments of Capitalized Interest pursuant to subsection 4.24(a)(iv)(B)
          hereof, Mortgagor shall not be permitted to prepay the principal
          balance of the Loan except as set forth in Section 5 of the Note.
          Deferred Interest Reduction Payments during the Reduced Payment Period
          and the Interest Only Payment Period, if any, may be made no more than
          once per month, and shall be remitted together with the regularly
          scheduled monthly payment of interest under the Note. Net Cash Flow
          shall not be used by Mortgagor for any purpose, other than as provided
          in this subsection 4.24(a).

          (b)   So long as no Event of Default has occurred, Mortgagor may make
          daily transfers of Net Cash Flow from the Property to a corporate bank
          account maintained by Guarantor (the "Central Account"), provided that
          Guarantor shall properly account for all funds so transferred as
          Mortgagor's funds. So long as no Event of Default has occurred, Net
          Cash Flow (as defined in subsection 4.24(d) hereof) from the Key
          Biscayne Property may be used to fund Operating Expenses (as defined
          in subsection 4.24(f) hereof) of the Property, and Net Cash Flow from
          the Property may be used to fund Operating Expenses of the Key
          Biscayne Property. So

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          long as no Event of Default has occurred, Mortgagor and Key Biscayne
          Borrower may calculate Gross Revenues, Operating Expenses, Net Cash
          Flow and Excess Cash Flow, for purposes of this Section 4.24, on a
          consolidated basis for both the Property and the Key Biscayne
          Property. Each month during the Reduced Payment Period and the
          Interest Only Payment Period, on or before the twentieth (20th) day of
          the month, Mortgagor shall remit to Mortgagee all Net Cash Flow for
          the prior month from the Property, or from the Property and the Key
          Biscayne Property on a consolidated basis, as applicable, which was
          not applied in accordance with subsections 4.24(a)(ii) or (iv) hereof
          (the "Excess Cash Flow"), if any. All Excess Cash Flow so received by
          Mortgagee shall be retained in an account (the "Additional Collateral
          Account") maintained by Mortgagee or an entity designated by Mortgagee
          to service the Loan ("Servicer"), and held as additional Collateral
          for the Loan. So long as no Event of Default has occurred, in months
          in which Gross Revenue from the Property (or from the Property and the
          Key Biscayne Property on a consolidated basis, as applicable) is
          insufficient to fund Operating Expenses of the Property (or of the
          Property and the Key Biscayne Property on a consolidated basis, as
          applicable), Mortgagor may obtain a disbursement of funds from the
          Additional Collateral Account in the lesser of (i) the amount
          necessary to pay the unpaid Operating Expenses for the subject month,
          or (ii) the balance in the Additional Collateral Account, less any
          minimum required balance required by the depository bank to be
          maintained therein, upon submission of a written request to Mortgagee
          or Servicer. So long as no Event of Default has occurred, Mortgagor
          may obtain a disbursement of funds from the Additional Collateral
          Account to make a Deferred Interest Reduction Payment to Mortgagee as
          provided in subsection 4.24(a)(iv), in the lesser of (i) the amount
          requested by Mortgagor to make the Deferred Interest Reduction
          Payment, or (ii) the balance in the Additional Collateral Account,
          less any minimum required balance required by the depository bank to
          be maintained therein, upon submission of a written notice to
          Mortgagee or Servicer.

          (c)   The annual operating statements for the Property described in
          Subsection 4.13 hereof shall indicate the amount of Net Cash Flow for
          each twelve month period from January 1 through December 31 included
          in the Reduced Payment Period and the Interest Only Payment Period,
          and shall certify (i) the application of Net Cash Flow for the
          relevant period to Capital Expenses, subject to Mortgagee's prior
          written approval to the extent that such Capital Expenses exceed the
          Capital Expense Limit; (ii) the payment of Net Cash Flow for the
          relevant period to Mortgagee for deposit in the Additional Collateral
          Account; and/or (iii) that

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          Deferred Interest Reduction Payment(s) to Mortgagee have been made in
          the amount of all remaining Net Cash Flow for the relevant period.

          (d)   For purposes of this Section 4.24, "Net Cash Flow" shall mean
          the difference between Gross Revenue and Operating Expenses for the
          applicable period.

          (e)   For purposes of this Section 4.24, "Gross Revenue" shall mean
          all revenue received by or on behalf of Mortgagor from or with respect
          to the Property for the relevant period for which the calculation of
          Gross Revenue is being made, including, but not limited to rents, room
          charges, parking fees, payments from tenants and other occupants of
          any portion of the Property or from the operation of the Property, and
          payments received from insurance on account of business or rental
          interruption and condemnation proceeds from any temporary use or
          occupancy. Gross Revenue shall not include: (i) proceeds from the sale
          or other disposition of any part or all of the Property, or from any
          financing or refinancing of the Property; (ii) proceeds from any
          condemnation of any part or all of the Property (except for temporary
          use or occupancy); (iii) proceeds on account of a casualty to the
          Property (other than payments from insurance on account of business or
          rental interruption); (iv) other insurance proceeds (other than in
          compensation of lost rent or its equivalent); (v) similar items or
          transactions, the proceeds of which under generally accepted
          accounting principles are deemed attributable to capital and are not
          in the nature of rent; and (vi) contributions or loans to Borrower by
          any member or affiliate of Borrower.

          (f)   For purposes of this Section 4.24, "Operating Expenses" shall
          mean all ordinary and necessary operating expenses actually incurred
          by Mortgagor in connection with the operation of the Property and the
          continued existence in good standing of Mortgagor for the relevant
          period for which the calculation of Operating Expenses is being made,
          including but not limited to (i) payments made to Mortgagee for taxes
          and insurance, if any, under the Mortgage, (ii) debt service as
          required by the Note (excluding Deferred Interest Reduction Payments),
          and (iii) actual Capital Expenses of the Property, not in excess of
          the Capital Expense Limit, paid in accordance herewith, but excluding
          (a) any non-cash expenditure, such as depreciation, and (b) any
          payment to a member or affiliate of Mortgagor, including, without
          limitation, payments to a member or affiliate of Mortgagor for
          management of the Property, not pre-approved by Mortgagee, but
          including management fees paid in accordance with a Management
          Agreement entered into by Mortgagor (if any) and approved by

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          Mortgagee. For purposes of this subsection 4.24(f), the fees, and the
          methods of calculation thereof, indicated on the "Corporate Fees and
          Charges Schedule" delivered by Mortgagor to Mortgagee on February 20,
          2004 have been pre-approved by Mortgagee.

          (g)   For purposes of this Section 4.24, "Capital Expenses" shall mean
          all cash expenditures for the Property that would be considered
          capital in nature under generally accepted accounting principles."

                (e)  A new Section 4.25 is hereby added to the Mortgage, as
                follows:

          "4.25 COVENANTS CONCERNING ACCOUNTS.

          (a)   During the term of the Loan, Mortgagor shall maintain the
          Pledged Operating Account as the exclusive account into which Gross
          Revenue from the Property shall be deposited.

          (b)   Unless and until Mortgagor has received written notice from
          Mortgagee that an Event of Default has occurred and specifying the
          Event of Default (any such notice being referred to herein,
          individually, as a "Default Notice"), (i) Mortgagor shall deposit all
          Gross Revenue received by or for the benefit of Mortgagor and
          attributable to the Property into the Pledged Operating Account, and
          (ii) funds on deposit in the Pledged Operating Account may be
          withdrawn by Mortgagor from time to time to pay Operating Expenses as
          and when due, to pay for Capital Expenses in amounts not to exceed the
          accrued Capital Expense Limit, and for transfer to the Central
          Account, subject to the restrictions contained in this Mortgage.

          (c)   After Mortgagor's receipt of a Default Notice, and during the
          continuance of any Event of Default, (i) Mortgagor shall deposit all
          revenues received by or for the benefit of Mortgagor and attributable
          to the Property into the Pledged Operating Account on the business day
          received by Mortgagor, and (ii) Mortgagor shall have no right to
          withdraw any funds in the Pledged Operating Account as contemplated in
          Section 4.25(b) above for any purpose, including without limitation
          for transfer to the Central Account.

          (d)   After Mortgagee has given any Default Notice, and during the
          continuance of any Event of Default, Mortgagee shall apply, or cause
          to be applied, as and when due, funds on deposit in the Pledged
          Operating Account and/or the Additional Collateral Account in the
          following order and priority:

                                                                              43
<Page>

                     (i)   first, to Mortgagor to pay actual Operating Expenses
          and/or, subject to Mortgagee's prior written consent, not to be
          unreasonably withheld, Capital Expenses, as set forth in a request for
          disbursement to be delivered no more than twice monthly by Mortgagor
          to Mortgagee;

                     (ii)  second, to Mortgagor, or Mortgagor's account, in
          payment of monthly amounts pursuant to the tax and insurance escrows,
          if any, for the Property required under this Mortgage;

                     (iii) third, to Mortgagee, or Mortgagee's account, in
          payment of any late charges, default interest and other sums
          previously due under the Note or other Loan Documents (other than
          regularly scheduled monthly payments due under the Note) and to
          repayment of any advances, costs, expenses or other payments owing by
          Mortgagor to Mortgagee under this Mortgage or the other Loan
          Documents; and

                     (iv)  fourth, to Mortgagee, or Mortgagee's account, in
          payment of the regularly scheduled monthly payment then due under the
          Note.

          (e)   Mortgagor shall deposit, and Mortgagor shall cause its agents
          and/or property manager or managers to deposit, all revenues received
          by or for the benefit of Mortgagor and attributable to the Property
          into the Pledged Operating Account by wire transfer or by direct or
          traditional deposit, and, if any such revenues are received by
          Mortgagor in the form of checks, drafts or other instruments then
          Mortgagor shall also immediately endorse (if applicable) and deposit
          same into the Pledged Operating Account."

                (f)  A new Section 4.26 is hereby added to the Mortgage, as
                follows:

          "4.26 APPRAISAL. On one occasion while any portion of the Secured
          Obligations remains unpaid, upon written request by Mortgagee,
          Mortgagor shall obtain and deliver to Mortgagee, at Mortgagor's
          expense, an MAI appraisal of the Property (a) made by an appraiser
          certified in the state where the Property is located and approved by
          Mortgagee, and (b) satisfactory to Mortgagee in all other respects."

                (g)  A new Section 4.27 is hereby added to the Mortgage, as
                follows:

          "4.27 CONSENT TO RELIEF FROM AUTOMATIC STAY. In the event of the
          filing of a petition in bankruptcy by or against Mortgagor under the
          United States Bankruptcy Code, Mortgagor consents and

                                                                              44
<Page>

          agrees to the entry of immediate relief from the automatic stay of
          section 362(a) of the Bankruptcy Code, and shall not contest any
          motion by Mortgagee for termination of, or other relief from, such
          automatic stay."

                (h)  A new Section 5.11 is hereby added to the Mortgage, as
                follows:

          "5.11 DISTRIBUTIONS TO OWNERS PRIOR TO PRINCIPAL AND INTEREST PAYMENT
          PERIOD. Without the prior written consent of Mortgagee, Mortgagor will
          not distribute any portion of the Gross Revenue from the Property to
          any other holder of a direct or indirect ownership interest in
          Borrower, prior to the commencement of the Principal and Interest
          Payment Period (as defined in the Note); provided, however, that
          payments to a member or affiliate of Mortgagor which have been
          pre-approved by Mortgagee, as described in subsection 4.24(f) hereof,
          shall be allowed."

                (i)  EXHIBIT B, Permitted Exception No. 1, of the Mortgage is
hereby deleted in its entirety, and the following substituted therefor: "Real
property taxes for the second half of fiscal year 2004 and for subsequent years
not yet due and payable."

          4.    MODIFICATION OF REPLACEMENT RESERVE AND SECURITY AGREEMENT. The
Replacement Reserve and Security Agreement, as previously modified by the
Modification Agreement, is further modified as follows:

                (a)  All references to the term "Note" contained in the
Replacement Reserve and Security Agreement shall be deemed to refer to the Note
as defined herein and as modified by this Agreement; all references to the term
"Loan" contained in the Replacement Reserve and Security Agreement shall be
deemed to refer to the loan evidenced by the Note.

                (b)  All references to the term "Mortgage" contained in the
Replacement Reserve and Security Agreement shall be deemed to refer to the
Mortgage, as defined herein and as modified by this Agreement.

                (c)  All references contained in the Replacement Reserve and
Security Agreement to the term "Loan Documents" shall be deemed to refer to such
term as defined herein and as modified by this Agreement.

                (d)  From the Effective Date until the earlier of (i) the
expiration of the Interest Only Payment Period (as defined in Section 4.24(a) of
the Mortgage), or (ii) the occurrence of a Reinstatement as set forth in Section
5 of this Agreement, Borrower's obligations to make monthly deposits to the
Replacement Reserve Account pursuant to Section 4 of the Replacement Reserve and
Security Agreement, to submit Capital Budgets pursuant to Section 6 of the
Replacement Reserve and Security Agreement, and to submit reports pursuant to
Section 8 of the Replacement Reserve and Security Agreement shall be suspended,
it being the intent of the parties that such obligations shall be superseded by
the provisions of the new Sections 4.24, 4.25 and 5.11 of the Mortgage during
such period.

                                                                              45
<Page>

                (e)  Any amounts on deposit in the Replacement Reserve Account
on the Effective Date may be withdrawn by Borrower and applied to Capital
Expenses during the Reduced Payment Period and/or the Interest Only Payment
Period with the prior written approval of Lender, which consent shall not be
unreasonably withheld or delayed.

                (f)  Upon the earlier of (i) the expiration of the Interest Only
Payment Period, or (ii) the occurrence of a Reinstatement as set forth in
Section 5 of this Agreement, Borrower's obligations to make monthly deposits to
the Replacement Reserve Account pursuant to Section 4 of the Replacement Reserve
and Security Agreement, to submit Capital Budgets pursuant to Section 6 of the
Replacement Reserve and Security Agreement, and to submit reports pursuant to
Section 8 of the Replacement Reserve and Security Agreement shall be fully
reinstated.

          5.    REINSTATEMENT. On the first day of any month during the Reduced
Payment Period or the Interest Only Payment Period, provided that no Event of
Default has occurred under the Note or any of the other Loan Documents, the
Borrower may effect a "Reinstatement" of the Loan by satisfying the following
conditions:

                (a)  Borrower shall deliver written notice to Lender, not less
than thirty (30) days prior to the Reinstatement, of Borrower's intent to effect
a Reinstatement; and

                (b)  On the date of the Reinstatement, Borrower shall pay all
accrued and unpaid interest on the Note, except any accrued and unpaid interest
which has been added to the principal balance of the Note.

Upon the occurrence of a Reinstatement pursuant to this Section 5:

                (a)  Section 1 of the Note shall be amended to provide that (i)
commencing on the date of the Reinstatement, and on the first day of each month
thereafter through and including June 1, 2010, combined payments of principal
and interest shall be payable, in arrears, in the amount of $332,910.63; and
(ii) the entire outstanding principal balance of the Note, together with all
accrued and unpaid interest and all other sums due thereunder, shall be due and
payable in full on the Original Maturity Date.

                (b)  Borrower's obligations to submit monthly Net Cash Flow
Reports pursuant to Section 4.13 of the Mortgage shall be terminated.

                (c)  Sections 4.24, 4.25 and 5.11 of the Mortgage shall be
terminated and of no further effect.

                (d)  Borrower's obligations to make monthly deposits to the
Replacement Reserve Account pursuant to Section 4 of the Replacement Reserve and
Security Agreement, to submit Capital Budgets pursuant to Section 6 of the
Replacement Reserve and Security Agreement, and to submit reports pursuant to
Section 8 of the Replacement Reserve and Security Agreement shall be fully
reinstated.

                6.   MODIFICATION OF ENVIRONMENTAL INDEMNITY AGREEMENT. The
Environmental Indemnity Agreement dated as of December 16, 1996, executed by
Borrower and

                                                                              46
<Page>

Guarantor, as previously modified by the Modification Agreement and by the
Reaffirmation and Modification of Limited Guaranty Agreement and Environmental
Indemnity Agreement dated as of May 30, 2000 executed by Guarantor for the
benefit of Borrower (as so modified, the "Environmental Indemnity Agreement"),
is further modified as follows:

                (a)  All references to the term "Note" contained in the
Environmental Indemnity Agreement shall be deemed to refer to the Note as
defined herein and as modified by this Agreement; all references to the term
"Loan" contained in the Environmental Indemnity Agreement shall be deemed to
refer to the loan evidenced by the Note.

                (b)  All references to the term "Mortgage" contained in the
Environmental Indemnity Agreement shall be deemed to refer to the Mortgage, as
defined herein and as modified by this Agreement.

                (c)  All references contained in the Environmental Indemnity
Agreement to the term "Loan Documents" shall be deemed to refer to such term as
defined herein and as modified by this Agreement.

                (d)  In consideration of Lender's willingness to enter into this
Agreement, Borrower hereby reaffirms all of its agreements and obligations under
the Environmental Indemnity Agreement, as modified by the Modification Agreement
and hereby.

          7.    MODIFICATION OF OTHER LOAN DOCUMENTS.

                (a)  All references to the term "Note" contained in the Loan
Documents shall be deemed to refer to the Note as defined herein and as modified
by this Agreement; all references to the term "Loan" contained in the Loan
Documents shall be deemed to refer to the loan evidenced by the Note.

                (b)  All references to the term "Mortgage" contained in the Loan
Documents shall be deemed to refer to the Mortgage as defined herein and as
modified by this Agreement.

                (c)  All references contained in any of the Loan Documents to
the term "Loan Documents" shall be deemed to refer to such term as defined
herein and as modified by this Agreement.

          8.    REAFFIRMATION OF LOAN DOCUMENTS.

                (a)  Borrower hereby re-makes each and every representation and
warranty of Borrower to Lender contained in Article III of the Mortgage and
Section 1 of the Environmental Indemnity Agreement, each as modified hereby.

                (b)  As modified hereby, the terms and provisions of the
Mortgage and the other Loan Documents are hereby ratified and confirmed, and
shall be and remain in full force and effect, enforceable in accordance with
their terms.

                                                                              47
<Page>

          9.    GRANT OF LIEN AND SECURITY INTEREST.

                (a)  Borrower hereby acknowledges and confirms that the
Mortgage, as modified hereby, constitutes a first priority security conveyance
of and first lien on the Property, subject only to the Permitted Exceptions set
forth therein.

                (b)  In consideration of Lender's willingness to enter into this
Agreement and as security for Borrower's obligations under the Note and the
other Loan Documents and Key Biscayne Borrower's obligations under the Key
Biscayne Note and the Key Biscayne Loan Documents (as such terms are defined in
the Mortgage), Borrower hereby (a) grants, bargains, sells, conveys, mortgages
and warrants with MORTGAGE COVENANTS unto Lender the entire right, title,
interest and estate of Borrower in and to the Property, whether now owned or
hereafter acquired; TO HAVE AND TO HOLD the same, together with all and singular
the rights, hereditaments, and appurtenances in anywise appertaining or
belonging thereto, unto Lender and Lender's successors, substitutes and assigns
forever, and (b) grants to Lender a security interest in the Property, Chattels
and Intangible Personalty (as defined in the Mortgage, as modified hereby), each
on the terms and conditions set forth in the Mortgage, as modified hereby.

          10.   STATUTORY CONDITION. This Agreement is upon the STATUTORY
CONDITION, and upon the further condition that each of the aforementioned
covenants, agreements, representations and warranties shall be kept and duly
performed. If there shall occur a breach of any of such conditions which
constitutes an Event of Default under the Loan Documents, or if the entire
mortgage debt becomes due at the option of Lender, the holder hereof shall have
the STATUTORY POWER OF SALE, and, as to the Collateral (as defined in the
Mortgage, as modified hereby), all rights and remedies conferred by the Uniform
Commercial Code.

          11.   ENDORSEMENT TO LENDER'S TITLE INSURANCE POLICY. Upon
closing of the loan restructure transaction described in this Agreement,
Borrower shall deliver to Lender, at Borrower's sole expense, an endorsement to
Lender's title insurance policy or a new title insurance policy, satisfactory in
form and substance to Lender, issued by a title insurance company approved by
Lender, in an amount not less than the amount of the Loan, insuring Lender that
the Mortgage as modified by this Agreement is a valid first and prior lien on
the Property, subject only to such exceptions to and conditions of title as
Lender may approve, and containing such additional endorsements as Lender may
require including, without limitation, a tie-in endorsement aggregating such
title insurance coverage with the title insurance coverage insuring the lien of
the Key Biscayne Second Mortgage.

          12.   OPINION OF BORROWER'S COUNSEL. Upon closing of the loan
restructure transaction described in this Agreement, Borrower shall deliver to
Lender a legal opinion of independent counsel to Borrower, in form and substance
satisfactory to Lender, opining that the Loan as restructured is not usurious
under any applicable law, that the loan restructure transaction and the
execution and delivery of all documents in connection therewith have been duly
authorized by all necessary parties (other than Lender), and that all such
documents are binding and enforceable in accordance with their terms, and
addressing such other matters as Lender may reasonably require.

                                                                              48
<Page>

          13.   PAYMENT OF COSTS AND EXPENSES. Borrower shall pay all
costs and expenses incurred by Lender in connection with this Agreement and in
connection with the restructure of the Loan, including, without limitation, all
reasonable attorneys' fees, recording fees and title insurance fees (including
the fees for issuance of the endorsement to Lender's title insurance policy or a
new title insurance policy, as applicable) deemed necessary by Lender. Such
costs and expenses shall be paid by Borrower upon closing of the loan
restructure transaction described in this Agreement ("Closing"). Such costs and
expenses shall be considered Operating Expenses of the Property, as defined in
subsection 4.24(f) of the Mortgage, for the period in which they are paid by
Borrower. Failure to pay such costs and expenses upon Closing shall constitute a
default by Borrower under Section 6.3 of the Mortgage, and continuance of such
failure for a period of thirty (30) days following written notice thereof from
Lender to Borrower shall constitute an Event of Default under the Mortgage.

          14.   MISCELLANEOUS.

                (a)  All capitalized terms used herein without definition shall
have the meanings given to them in the Mortgage.

                (b)  This Agreement may be executed in several counterparts, and
executed counterparts bearing signatures of Borrower and Lender shall constitute
a fully-executed original of this Agreement.

                (c)  This Agreement shall be governed by the laws of the
Commonwealth of Massachusetts, without giving effect to its principles of
conflicts of laws.

                (d)  The parties hereby agree to execute any and all additional
documents that may reasonably be required in order to evidence, secure or carry
out the agreements and undertakings set forth in this Agreement.

                (e)  This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their permitted successors and assigns.

                (f)  EACH PARTY TO THIS AGREEMENT KNOWINGLY, IRREVOCABLY,
VOLUNTARILY AND INTENTIONALLY WAIVES ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN
RESPECT OF ANY ACTION, PROCEEDING OR COUNTERCLAIM BASED ON THIS AGREEMENT, OR
ARISING OUT OF, UNDER OR IN CONNECTION WITH THE NOTE, THE MORTGAGE OR ANY OTHER
LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENT (WHETHER
VERBAL OR WRITTEN) OR ACTIONS OF ANY PARTY HERETO OR TO ANY LOAN DOCUMENT OR
ORIGINAL LOAN DOCUMENT. THIS PROVISION IS A MATERIAL INDUCEMENT FOR THE PARTIES
TO ENTER INTO THE TRANSACTIONS EVIDENCED BY THIS AGREEMENT.

                (g)  Borrower shall not deposit funds attributable to the
Property into the Pledged Operating Account unless and until a Notice of
Assignment and Control Agreement concerning such account, in form and substance
satisfactory to Lender, has been executed by Borrower, Lender and the depository
bank at which the account is maintained, and a fully

                                                                              49
<Page>

executed original of such Notice of Assignment and Control Agreement has been
delivered to Lender.

                   [BALANCE OF PAGE INTENTIONALLY LEFT BLANK]

                                                                              50
<Page>

          IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date set forth above.

                              BORROWER:

                              --------------------------------------------------
                              Roger P. Sonnabend, Trustee of the Charterhouse of
                              Cambridge Trust, and not individually

                              /S/
                              --------------------------------------------------
                              Peter J. Sonnabend, Trustee of the Charterhouse of
                              Cambridge Trust, and not individually

                              /S/
                              --------------------------------------------------
                              Boy A.J. van Riel, Trustee of the Charterhouse of
                              Cambridge Trust, and not individually

                              SONESTA OF MASSACHUSETTS, INC., a
                              Massachusetts corporation

                              By: /S/
                                  ----------------------------------------------
                                  Peter J. Sonnabend, Vice President

                              LENDER:

                              SUNAMERICA LIFE INSURANCE COMPANY,
                              an Arizona corporation

                              By:/S/
                                 ----------------------------------------------
                              Name:  Keith C. Honig
                                     -------------------------------------------
                              Title: Authorized Agent
                                     -------------------------------------------

                                       A-

                                                                              51

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