Africa Hall is the permanent headquarters of UNECA, the United Nations Economic Commission for Africa. The structure, built in the span of only 18 months, was completed in February 1961. It covers an overall area of 75,000 m2, with a usable area of 13,800 m2, consisting of 3,600 m2 of conference halls, 5,500 m2 of offices and 4,700 m2 of general facilities. Its main characteristic is represented by the “continuous spaces” of the internal layout. Ten years later, in 1971, work was commenced on a project funded by the United Nations to extend the structure, which was completed in 1975. It consists of a block of 800 new offices, a 6-storey building to house the huge library and other buildings for general facilities. This extension work added a further 130,000 m2.