||The Cobra Room, Secret Tunnels, Bomb Shelters, Crypts, Lost Rivers, Trains & Drains: ‘Nowhere else is the tangle of infrastructure - new and old - with history and geology more intriguing or problematic’. (from Beneath the Metropolis The Secret Lives of Cities Alex Marshall). The London we know is just the crust: there's another world down there. Everything from the squat, camouflaged, granite-hard redoubt where the last stand would be made against the Nazis to the ultra-secret Cobra Room. Find out what’s under your feet with a guide who can show you the tell-tale ripples on the surface: vents, secret doorways, emergency exits, the "last stand" redoubt. The old familiar London will never look the same again.