The headquarters of the United Nations is a complex in New York City. The complex has served as the official headquarters of the United Nations since its completion in 1952. It is located in the Turtle Bay neighborhood of the borough of Manhattan, on spacious grounds overlooking the East River. Its borders are First Avenue on the west, East 42nd Street to the south, East 48th Street on the north and the East River to the east. Turtle Bay is occasionally used as a metonym for the U.N. headquarters or for the U.N. as a whole.

The United Nations has three additional, subsidiary, regional headquarters or headquarter districts. These are located in Geneva (Switzerland), Vienna (Austria), and Nairobi (Kenya). These adjunct offices help represent UN interests, facilitate diplomatic activities, and enjoy certain extraterritorial privileges, but only the main headquarters in New York contains the seats of the principal organs of the UN, including the General Assembly and Security Council. All fifteen of the United Nations' specialized agencies are located outside New York at these other headquarters or in other cities.