Cities of the UnderworldIn every major metropolis, skyscrapers loom above, taxis and vendors clamor at street level, and subways rumble below. But deeper beneath the hectic surface lie other, silent worlds, each with its own mysterious and fascinating history.

Cities of the Underworld peels away the layers of time-often literally hundreds of feet thick-to expose the incredible pasts lurking beneath some of the most populous cities on earth.

Throughout the world, cities such as Paris, New York, Rome and Shanghai all harbor long-submerged networks that once served crucial functions, from eerie catacombs to clandestine hideouts and ancient aqueducts to underground societies.

Cities of the Underworld examines these mysterious realms, from the technological feats of their construction and the myths and lore that have cloaked these subterranean marvels for centuries.

Featuring rare location hi-definition footage, The History Channel shows a world filled with mysteries and secrets just below the ground we walk on.

Watch the full documentary now (playlist - )