One of the sleekest residential towers to open in the city in 2006 is this 31-story, residential condominium building at 310 East 53rd Street on the southeast corner at Second Avenue.

The developer is Macklowe Properties, which has developed such major apartment towers such as RiverTower at 420 East 54th Street, RiverTerrace at 515 East 72nd Street, the Metropolitan Tower at 136 East 57th Street and 145 East 76th Street.

This tower tower was designed by SLCE Architects and has a free-standing, blue-glass tower set on a five-story limestone-clad base.

The building has 88 apartments and offers four kinds of residences: "mansions," which are located in the base and are 40-foot-high duplexes with wood-burning fireplaces that have three bedrooms and a library, 4? baths and 20 feet ceilings, one of which, with 3,913 square feet, was priced initially at $6,900,000 with estimated monthly common and real estate tax charges without 421A abatement is $4,507; duplex studios, which are also located in the base, and have one-bedroom, two baths and 20 foot-high ceilings, one of which, with 1,928 square feet, is priced at $2,024,400; tower residences, some of which have two bedrooms, a library 2? baths and 222 square-foot balconies, with prices ranging from $2,719,686 to $2,984,911, and some of which have three bedrooms, 3? baths and 146-square-foot balconies, with prices ranging from $3,285,700 to $3,996,00; and the triplex penthouse, which is priced "on request."

The building has a 24-hour doorman and concierge, a fitness center, a roof deck, valet parking in the building, and a garden. The apartments have walk-in closets and large entrance galleries.