This book is the first concise guide to the hidden world of underground London. Informative, authoritative and richly illustrated, this volume takes you on a subterranean tour of the many remarkable constructions that few even knew existed. Some of the installations were once highly secret, such as the government bunkers, civilian refuges, protected broadcasting studios and emergency control centres for public utilities. Other facilities described perform more mundane functions, including the mothballed Mail Rail (the Post Office Railway), telephone and power cable subways, electricity substations and sewage out-fall tunnels.