One United Nations Plaza (New York City, New York)

 office building, skyscraper, 1976_construction, postmodern (architecture)

505-foot, 39-story modernist office building completed in 1975, followed six years later by its semi-twin tower in the United Nations Plaza complex, Two United Nations Plaza. Both were designed by Kevin Roche John Dinkeloo & Associates, and they share a 1-story base, with a glass-and-metal covered plaza area on 44th Street. They are also linked by a skybridge. Both towers are clad in reflective green glass in silver aluminum framing, with distinctive angular, folded forms.

The lower floors are office space, while the hotel is on floors 28-39. The hotel original opened as the United Nations Hotel when One United Nations Plaza was finished in 1975. With the construction of the second tower, the lobby space was enlarged and moved to the connecting base area, with a long frontage along 44th Street. The hotel was later managed for two decades by Hyatt, and currently operates as the Millennium Hilton One U.N. Plaza. Farther east on 44th Street is the entrance to the Ambassador Grill. At the chamfered southeast corner is an entrance to a Chase Private Client bank branch on the ground floor, and the main entrance for the office building is centered on 1st Avenue.

There is a swimming pool and health club on the 27th floor, and a tennis court on the tower's top floors.