Episode guide

Underground Worlds

Series 1

Underground Worlds

  • Sweden

    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.

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  • Switzerland

    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.

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  • Bouzincourt

    A labyrinth of tunnels underneath a tiny French village which contains mysteries from several historical eras, and a Welsh slate mine that has been given a new lease of life.

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  • 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.

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  • 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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  • Gibraltar

    Incredible feats of human endeavour, revealing what people have built, where they've built it, how and why. The first edition focuses on hidden tunnels and caves in Gibraltar.

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  • Jersey War Tunnels

    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.

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  • The Maginot Line

    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.

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  • Edinburgh Vaults

    The sinister history of Edinburgh's vaults and the development of Helsinki's subterranean spaces. Plus, the impact of the building of Naples on the volcanic ground below.

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  • Dover War Rooms

    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.

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