S1 E6 ∙ City of Naours ∙

An underground city beneath a forest in Northern France built to house 3,000 people, an ice cave under Iceland's biggest glacier, and a subterranean power station in London.

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All episodes for series 1 of Underground Worlds

S1 E1 · Gibraltar

Incredible feats of human endeavour, revealing what people have built, where, how and why.

S1 E3 · Switzerland

A look at some of Switzerland's 300,000 subterranean bunkers built across history.