Beneath Moscow there is said to be a second, secret metro for the country's leaders. Parts of the story are documented, and the rest is rumour that nobody in power will confirm.
Behind an ordinary-looking bungalow in the Essex countryside, a 100-yard tunnel leads down to a three-level bunker about 125 feet underground. Built in 1952 as an RAF command centre, it became a regional government headquarters for a nuclear war, and is now a museum.