From Wikipedia: The Churchill War Rooms is a museum in London and one of the five branches of the Imperial War Museum. The museum comprises the Cabinet War Rooms, a historic underground complex that housed a British government command centre throughout the Second World War, and the Churchill Museum, a biographical museum exploring the life of British statesman Winston Churchill. As a branch of a national museum, the Churchill War Rooms is supported by the Department for Culture, Media and Sport, by admissions income and the museum's commercial activity.
Construction of the Cabinet War Rooms, located beneath the Treasury building in the Whitehall area of Westminster, began in 1938. They became operational in August 1939, shortly before the outbreak of war in Europe. They remained in operation throughout the Second World War, before being abandoned in August 1945 after the surrender of Japan. After the war the historic value of the Cabinet War Rooms was recognised. Their preservation became the responsibility of the Ministry of Works and later the Department for the Environment, during which time very limited numbers of the public were able to visit by appointment. In the early 1980s the Imperial War Museum was asked to take over the administration of the site, and the Cabinet War Rooms were opened to the public in April 1984. The museum was reopened in 2005 following a major redevelopment, as the Churchill Museum and Cabinet War Rooms but in 2010 this was shortened to the Churchill War Rooms.