The Churchill War Rooms is a museum in London and one of the five branches of the Imperial War Museum. That small door wedged between the stairs and the building is the entrance to the Cabinet War Rooms and the Churchill Museum, together called the Churchill War Rooms. 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. The Churchill Museum, tracing the tumultuous life of the man some have even nicknamed “the greatest Briton”: Sir Winston Churchill.