S1 E4 ∙ Kingdom of Salt ∙
The Wieliczka Salt mine in Poland, some 327 metres deep, where the voids left behind from excavating salt have been transformed into extraordinary spaces, carved by hand.
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 E2 · Sweden
Exploring Sweden's passion for subterranean spaces.
S1 E3 · Switzerland
A look at some of Switzerland's 300,000 subterranean bunkers built across history.
S1 E4 · Kingdom of Salt
The wonders of the Wieliczka Salt mine in southern Poland.
S1 E5 · Bouzincourt
A labyrinth of tunnels underneath a tiny French village.
S1 E6 · City of Naours
An underground city beneath a forest in Northern France built to house 3,000 people.
S1 E7 · Jersey War Tunnels
The underground bases built by the German army during the occupation of Jersey.
S1 E8 · The Maginot Line
The secrets of the largest subterranean fortress along France's border with Germany.
S1 E9 · Edinburgh Vaults
The sinister history of Edinburgh's underground vaults.
S1 E10 · Dover War Rooms
The military headquarters built beneath Dover Castle during the Second World War.
