what kind of work took place in the headquarters?
It holds the seats of the principal organs of the UN, including the General Assembly and the Security Council.
Headquarters of the United Nations
The headquarters holds the seats of the principal organs of the UN, including the General Assembly and the Security Council, 
where is the headquaters of the united nation situated New York City . who is the design of this headquarters attributed to? A board of architects led by Wallace Harrison. where is this person from? United states of America. and what was he by profession? An architect. was the headquarters situated at an earlier place before? Yes, there were a number of temporary sites where this was located. when did the construction of this place first begin? 14 September 1948.
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Headquarters of the United Nations [SEP] Introduction
The headquarters holds the seats of the principal organs of the UN, including the General Assembly and the Security Council, but excluding the International Court of Justice, which is seated in the Hague. The United Nations has three additional subsidiary regional headquarters, or headquarters districts. These were opened in Geneva (Switzerland) in 1946, Vienna (Austria) in 1980, and Nairobi (Kenya) in 1996. These adjunct offices help represent UN interests, facilitate diplomatic activities, and enjoy certain extraterritorial privileges, but do not contain the seats of major organs. Although it is in New York City, the land occupied by the United Nations Headquarters and the spaces of buildings that it rents are under the sole administration of the United Nations and not the U.S.