United Nations Headquarters, New York, NY 10017, USA. 

Construction started on 24 October 1949 and was completed on 21 August 1950, 19 months later. The total cost was 65 million dollars, cut by 20 million from the original 85 million budget by reducing the height of the Secretariat Building from 45 to 39 storeys, for example. 

The complex consists of 4 main buildings on 18 acres. The Secretariat Building is the tallest, reaching 550 feet, i.e. 167.6 meters. It has 39 stories above ground and 3 underground. Total office space is 20 acres with an amazing amount of 4,000 air conditioners. 

$loop$The General Assembly building has concave sides 380 feet long and 160 feet wide. That is 115.8 and 48.8 meters. The blue, green and gold General Assembly Hall, 165 feet long by 115 feet wide, occupies the 2nd, 3rd and 4th floors. The General Assembly first met in this Hall at the opening of its 7th regular annual session on 14 October 1952. 

The Hall has 1,321 seats and accommodates 191 delegations. Each delegation has 6 seats, 3 for full delegates and 3 for alternates. The Gallery on the 3rd floor has 244 seats for alternates, representatives of some special agencies and other senior officers. In a balcony above is a row of 53 seats for news media and 280 seats in 5 rows for the public. 

On 2 lower levels of the building are a large conference room, with 623 seats in the delegates' area, 44 seats for the press, and 166 seats for the public, and 4 smaller conference rooms, and some other facilities. 

The UN Headquarters was designed to serve 4 major groups: delegations, who now represent 191 Member States and who send more than 5,000 persons to New York each year; the secretariat, numbering about 4,700 persons in New York out of a total of about 9, 000 throughout the world; visitors, who average 700,000 yearly; and journalists, of whom more than over 3,600 are permanently accredited while over 10,000 are present during major meetings. 