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.