Underground Worlds

For centuries, people have built mind-blowing structures underground. This new and exclusive series reveals incredible feats of human endeavour and reveals what people have built, how they built it and why.

Underground Worlds

Underground Worlds

Series 1 | Episode 10

Exploring the military headquarters built beneath Dover Castle during the Second World War, and Odessa's catacombs, possibly the largest tunnel network in the world.

Underground Worlds

Underground Worlds

Series 1 | Episode 8

The secrets of the largest subterranean fortress along France's border with Germany, and a look at how a unique precious mineral was discovered in Derbyshire.

Underground Worlds

Underground Worlds

Series 1 | Episode 7

The underground bases built by the German army during the occupation of Jersey, and a group of more than 20 underground cities in Turkey, one of which dates back to 800BC.

Underground Worlds

Underground Worlds

Series 1 | Episode 2

Exploring Sweden's passion for subterranean spaces, and how the nation has taken extraordinary precautions to protect itself - by excavating an astounding 65,000 nuclear bunkers.

Underground Worlds

Underground Worlds

Series 1 | Episode 6

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.

Underground Worlds

Underground Worlds

Series 1 | Episode 3

A look at some of Switzerland's 300,000 subterranean bunkers, the creation of a local entrepreneur shrouded in mystery in England and a network of tunnels deep beneath Slovenia.

4 Hidden Places You Never Knew Existed

4 Hidden Places You Never Knew Existed

Here are just four of the strangest subterranean spots you never knew were there.