While the first meetings of the General Assembly and the Security Council were convened at the Methodist Central Hall in London, they quickly selected New York City for their headquarters and the home of the General Assembly.

Construction began in 1948 in Turtle Bay, a neighborhood previously known for its slaughterhouses. Nelson Rockefeller had previously bought the land from developer WIlliam Zeckendorf and provided it the United Nations for free.

In keeping with its general body, the United Nations Building wasn't designed by a singular architect, but instead a group of them. Overseen by architect Wallace Harrison, the group was made up of architects, planners, and engineers that were nominated by their respective member states.

The body was made up of the following: Sven Markelius, (Sweden), Le Corbusier (France), Ssu-ch'eng Liang (China), G.A. "Guy" Soilleux (Australia), Nikolai Bassov (Soviet Union), Ernest Cormier (Canada), Gaston Brunfaut (Belgium), Howard Robertson (United Kingdom), Julio Vilamajó (Uruguay) and Oscar Niemeyer (Brazil).

Le Corbusier initially tried to convince Niemeyer not to submit a plan to the board, stating that there was already a lot of division in the board. However, Niemeyer eventually submitted a plan which was chosen over Le Corbusier's.

While Harrison included elements from both plans in the design, it skewed much closer to Niemeyer's, with a distinctive building for the general assembly and a tower for the secretariat. Le Corbusier requested to shift the assembly hall, which destroyed Niemeyer's conception of a central square, but Niemeyer conceded to it.

Construction was helped along by the assistance by Robert Moses, New York's famously powerful construction coordinator who had helped in the lobbying of New York for the site of the United Nations.

On August 22nd, 1952, the United Nations was opened for the 450 workers of the secretariat. Its grounds are extraterritorial and controlled by the United Nations (though the UN accedes to most local, state, and federal laws.)