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.
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.
Incredible feats of human endeavour, revealing what people have built, where, how and why.
Exploring Sweden's passion for subterranean spaces.
A look at some of Switzerland's 300,000 subterranean bunkers built across history.
The wonders of the Wieliczka Salt mine in southern Poland.
A labyrinth of tunnels underneath a tiny French village.
An underground city beneath a forest in Northern France built to house 3,000 people.
The underground bases built by the German army during the occupation of Jersey.
The secrets of the largest subterranean fortress along France's border with Germany.
The sinister history of Edinburgh's underground vaults.
The military headquarters built beneath Dover Castle during the Second World War.