550 Madison Avenue, Postmodern skyscraper on Madison Avenue, Manhattan, United States

550 Madison Avenue is a 37-story, 647-foot (197 m) postmodern office tower completed in 1984, with a facade of pink granite. A large entrance arch faces east toward Madison Avenue, flanked by arcades with smaller flat arches. The roofline ends in a broken pediment with a circular opening, sometimes likened to a Chippendale cabinet top.

Designed by Philip Johnson and John Burgee, 550 Madison Avenue was announced in March 1978 and completed in 1984 as AT&T's headquarters, replacing 195 Broadway. The Bell System breakup of 1982 meant AT&T never filled the tower as planned. Sony leased it in 1991, bought it in 2002, sold it in 2013, and the Olayan Group acquired it in 2016; the exterior was designated a city landmark in 2018.

The broken pediment at the top, with its circular opening, is nicknamed the "Chippendale" after the open pediments of that English cabinetmaker's furniture. The entrance arch rises about seven stories, and the design was controversial from its announcement in March 1978. The lobby once held Spirit of Communication, a 7-metre bronze by Evelyn Beatrice Longman modelled in 1916, moved there in 1983 and relocated near Basking Ridge in 1992.

The main entrance arch faces Madison Avenue, with smaller flat-arched arcades flanking it. The block runs between 55th and 56th Streets, and the tower occupies the eastern part of the lot, next to the Corning Glass Building to the west. The office floors are reached from a sky lobby above the base, not from the street-level lobby.

The absence of setbacks was a zoning trade-off: the midblock pedestrian atrium let the tower rise higher than would otherwise have been allowed. The top is a broken pediment with a circular opening, likened to the open pediments of Thomas Chippendale's furniture, which earned the nickname "Chippendale" and drew mixed opinion from the moment the design was announced in March 1978.