The complex includes three major buildings: the Secretariat (the 39-floor office tower), the General Assembly building (where all member nations of the United Nations meet in the UN General Assembly), and the Dag Hammarskjöld Library. It is also notable for its gardens and outdoor sculpture.

The site of the United Nations headquarters is considered international territory, which means local laws do not apply. In addition, many of the diplomats working there have diplomatic immunity and so cannot be prosecuted by local courts. In the 1990s, however, the New York City government took steps to force diplomats to abide by local laws when living and traveling outside the U.N. headquarters, especially those concerning parking tickets and drunk driving.