The Palais des Nations is a complex of buildings that were built between 1929 and 1937 in the Ariana Park, Geneva (Switzerland). It served as the headquarters of the League of Nations (SDN) until 1946. It was later occupied by the United Nations Organisation and in 1966, the palace was turned into its European headquarters (Office of the United Nations Organisation in Geneva or UNOG) and it is the second most important organisation behind the headquarters in New York. Since its completion in 1937, the Palais des Nations has had two extensions: in 1950-1952 and in 1968-1973. The second phase finished with the construction of the "New Building" (Building E) to meet the growing need for conference facilities. In this context, Room XX was designed to become one of the council’s most important conference centres in Geneva.

Room XX, was also one of the largest conference rooms at the Palais des Nations, and since its refurbishment has become one of the most modern and fashionable. It is equipped with the latest design and technology and has a modular structure allowing many different configuration options, and could become the benchmark for future renewals of the United Nations buildings throughout the world.