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. Construction of the Cabinet War Rooms, located beneath the Treasury building in the Whitehall area of Westminster, began in 1938. They became fully operational on 27 August 1939, a week before Britain declared war on Germany. The War Rooms 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 title was shortened to the Churchill War Rooms. Construction In 1936 the Air Ministry, the British government department responsible for the Royal Air Force, believed that in the event of war enemy aerial bombing of London would cause up to 200,000 casualties per week. British government commissions under Warren Fisher and Sir James Rae in 1937 and 1938 considered that key government offices should be dispersed from central London to the suburbs, and nonessential offices to the Midlands or North West. Pending this dispersal, in May 1938 Sir Hastings Ismay, then Deputy Secretary of the Committee of Imperial Defence, ordered an Office of Works survey of Whitehall to identify a suitable site for a temporary emergency government centre. The Office concluded the most suitable site was the basement of the New Public Offices (NPO), a government building located on the corner of Horse Guards Road and Great George Street, near Parliament Square. The building now accommodates HM Treasury. Work to convert the basement of the New Public Offices began, under the supervision of Ismay and Sir Leslie Hollis, in June 1938. The work included installing communications