Churchill War Rooms, King Charles Street
On tour with our guide, Toby, from Mirandus Tours.
From Wikipedia: "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."