The city's Landmarks Preservation Commission unanimously approved today a declaration supporting an application by RFR Realty LLC, to the City Planning Commission for a special permit waiving setback and height regulations for the transfer of air rights from the Seagram Building at 375 Park Avenue, which it owns, to an adjacent site at 610 Lexington Avenue for the erection of a 709-foot-high, mixed-use tower.

Aby Rosen, one of the principals of RFR Realty LLC, told CityRealty.Com that the building will contain 80 to 90 condominium apartments and 45 to 50 hotel rooms.

Mr. Rosen said that the new tower will only utilize about 90 percent of the available, unused air rights from the Seagram Building, which only occupies 52 percent of its site and is widely regarded as an icon of modern architecture.

Mr. Rosen said that Hines, the Houston-based developer and real estate owner that owns the third property on the block, the 36-story, black-glass-clad tower formerly known as Manhattan Tower at 600 Lexington Avenue will be the construction manager for the new tower.

Sir Norman Foster of Foster and Partners, the architect of the new tower, told the commission that the new tower, which will rise without setbacks, will be set back 10 feet from 53nd Street and in plan it will be only 90 by 46 feet. The tower's entrance is setback in an atrium on 53rd Street and a low-rise "pavilion" will maintain the street-wall with retail uses on Lexington Avenue. He said that the very slender tower will be separated from the tower of the 515-foot-high Seagram Building by 117 feet.

RFR Realty LLC recently bought the mid-rise building at 610 Lexington Avenue, the former home of the YWCA, on the southwest corner of 53rd Street, cattycorner to

Citicorp Center, which is 915 feet high. RFR also owns Lever House on Park Avenue and developed 425 Fifth Avenue and are nearing completion of Park Avenue Place at 60 West 55th Street.

Foster and Partners designed the new notched tower addition to the Hearst Building now nearing completion on the southeast corner of Eighth Avenue and 57th Street. Sir Norman Foster is widely regarded as one of the world's foremost "high-tech" architects and his famous projects include the Hongkong and Shanghai Bank Headquarters in Hong Kong, the Commerzbank Headquarters in Frankfurt, Germany, and the Great Court at the British Museum in London.

Under the terms of the "74-79" application that will go before the City Planning Commission, the developers will pledge to restore and maintain the landmark Seagram Building and will establish a covenant with the New York Landmarks Conservancy, a civic organization, to that effect. Spokespersons for the Municipal Art Society and the New York chapter of the American Institute of Architects, said their groups supported it.

A spokesperson for the Historic Districts Council, however, told the commission that "the new, enormous building" will have "a negative impact" on the Seagram Building and that her organization therefore does not support the project.

The presentation before the commission emphasized that the new tower would not be visible from street-level from directly across Park Avenue from the Seagram Building. Roberta Brandes Gratz, a member of the commission, remarked during the hearing that the new project was "quite exciting" given "the horror of images of how wrong this could be," adding that the design "almost feels natural."

Mr. Foster said that if the building were erected "as of right" it would be about 811 feet high, but he termed that scheme "not entirely successful."

Although the north and south facades of the tower will be straight, the east and west facades will have three 3-facet bays, Mr. Foster said, adding that the light-colored facades will contrast with the bronze-clad Seagram Building.