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                                                                   Exhibit 2.2



     FIRST AMENDMENT, dated as of December 19, 1997 (this "Amendment"), to the
Amended and Restated Agreement and Plan of Merger, dated as of December 18,
1997, by and among American Radio Systems Corporation, a Delaware corporation
("American"), CBS Corporation (formerly, Westinghouse Electric Corporation), a
Pennsylvania corporation ("Mergeparty"), and R Acquisition Corp., a Delaware
corporation ("Mergeparty Subsidiary").

                                   WITNESSETH:

     WHEREAS, American, Mergeparty and Mergeparty Subsidiary are parties to an
Agreement and Plan of Merger, dated as of September 19, 1997 (the "Original
Merger Agreement"), providing for the merger of Mergeparty Subsidiary with and
into American on the terms and conditions set forth therein; and

     WHEREAS, American, Mergeparty and Mergeparty Subsidiary have entered into
an Amended and Restated Agreement and Plan of Merger, dated as of December 18,
1997 (the "Restated Merger Agreement"), to make certain changes to the Original
Merger Agreement; and

     WHEREAS, American, Mergeparty and Mergeparty Subsidiary desire to amend the
Restated Merger Agreement.

     NOW, THEREFORE, in consideration of the premises and the representations,
warranties, covenants and agreements herein contained and other valuable
consideration, the receipt and adequacy whereof are hereby acknowledged, the
parties hereto hereby, intending to be legally bound, represent, warrant,
covenant and agree as follows:

     1. Capitalized terms used and not defined herein shall have the meanings
given to such terms in the Restated Merger Agreement.

     2. American hereby represents and warrants to Mergeparty and Mergeparty
Subsidiary as follows, which representations and warranties shall be deemed to
form part of the representations and warranties of American included in Article
Four of the Restated Merger Agreement for all purposes of the Restated Merger
Agreement: (a) Annex 1 to this Amendment sets forth a list of certain
stockholders of American (the "Consenting Stockholders") and the number of
shares of American Class A Common and American Class B Common owned of record by
each such stockholder on the date hereof, (b) on the date hereof, 29,966,377
votes constituted a majority of the outstanding voting power of American Common
Stock and (c) on the date hereof the Consenting Stockholders have delivered
written consents to American approving and adopting the Restated Merger
Agreement and the Tower Merger Agreement in accordance with Applicable Law,
including without limitation the DCL, such consents will, upon mailing by
American of the notice as described in paragraph 3 below, constitute the
Required Vote and no other approvals of the stockholders of American other than
such consents are required to effect either the Merger or the Tower Merger.

     3. American will, promptly after the execution of this Amendment, mail, in
accordance with Section 228(d) of the DCL, notice of the corporate action
without a meeting taken by the Consenting Stockholders to those American
stockholders who have not consented to such action in writing and who, if the
action had been taken at a meeting of American 



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stockholders, would have been entitled to notice of the meeting if the record
date for such meeting had been the date that written consents signed by a
sufficient number of holders to take such action were delivered to American in
accordance with Section 228(c) of the DCL. The covenant of American in this
Section 3 shall be deemed to form part of the covenants of American included in
Article Six of the Restated Merger Agreement for all purposes of the Restated
Merger Agreement.

     4. All references to "Proxy Statement" in the Restated Merger Agreement
shall be deemed in all cases in the Restated Merger Agreement to be references
to "Information Statement" and all references to "Tower Proxy Statement" shall
be deemed in all cases in the Restated Merger Agreement to be references to
"Tower Information Statement."

     5. Notwithstanding anything contained in the Restated Merger Agreement to
the contrary, including without limitation Section 6.5 thereof, American shall
not be required to hold either the American Stockholders Meeting or the American
Stockholders Tower Meeting.

     6. This Amendment shall constitute a Collateral Document for all purposes
of the Restated Merger Agreement.

     7. The validity, interpretation, construction and performance of this
Amendment shall be governed by, and construed in accordance with, the Applicable
Laws of the United States of America and the laws of the State of New York
applicable to contracts made and performed in such State and, in any event,
without giving effect to any choice or conflict of laws provision or rule that
would cause the application of domestic substantive laws of any other
jurisdiction, except to the extent the corporate laws of the State of Delaware
are applicable.

     8. This Amendment may be executed in one or more counterparts, all of which
shall be considered one and the same agreement, and shall become effective when
one or more counterparts have been signed by each of the parties and delivered
to the other parties.

     9. Except as expressly modified and amended by this Amendment, the Restated
Merger Agreement shall continue in full force and effect and is hereby ratified
and confirmed in all respects.


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     IN WITNESS WHEREOF, American, Mergeparty and Mergeparty Subsidiary have
caused this Amendment to be executed, pursuant to the authority and approval of
each of their respective Boards of Directors, as of the date first written above
by their respective officers thereunto duly authorized.


                             American Radio Systems Corporation


                             By:
                                 -------------------------------------
                                 Name:  Steven B. Dodge
                                 Title: Chairman of the Board,
                                        President and Chief Executive Officer

                             CBS Corporation

                             By:
                                 -------------------------------------
                                 Name:  Frederic G. Reynolds
                                 Title:

                             Acquisition Corp.

                             By:
                                 -------------------------------------
                                 Name:  Frederic G. Reynolds
                                 Title:




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