Admiralty Citadel The West End

The ivy-covered concrete Admiralty Citadel is a heavily fortified, bomb-proof command and control fortress built for the Royal Navy in 1941 to prepare for a German land invasion. Sitting over a network of tunnels, the building has 20ft-thick concrete and steel walls (making it impossible to demolish), foundations 30ft deep and a lawn roof to render it invisible from an overhead reconnaissance.