Subterranean Silo Survival: Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall. Plus, former Atlas missile siloes in Kansas and tunnels hiding under Valetta. [S,AD]
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. [S]
Subterranean Silo Survival: Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall. Plus, former Atlas missile siloes in Kansas and tunnels hiding under Valetta. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Buried Lab of the Black Hills: Exploring a former gold mine turned scientific laboratory in South Dakota. Plus, limestone tunnels in London and a former water cistern in Denmark. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Mystery of the Kentucky Cave: Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years. [S,AD]
Ireland's Underground Alcatraz: Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for over 400 years. Plus, a former submarine base in the fjords of northern Norway. [S,AD]
Mystery of the Kentucky Cave: Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years. [S,AD]
Hotel Bunker of the Apocalypse: Exploring the secret, Cold War US government bunker hidden under Greenbrier Hotel, West Virginia; Plus, delve into the depths of a former slate mine in Wales, UK. [S,AD
Cincinnati's Secret Caverns: Exploring the forgotten underworld hiding beneath the streets of Cincinati, USA. Plus, a state-of-the-art Cold War fortress on the shores of Denmark. [S,AD]
Grand Canyon's Lost Treasure: Exploring inside the Grand Canyon Caverns - North America's largest dry cave system. Plus, Cold War radar bunkers around the UK. [S,AD]
Murder Raid Tunnels: Exploring the extensive air raid tunnels hidden beneath Ramsgate. Also, how the former thriving mining town of Butte, Montana repurposed the 10,000 miles of tunnels. [S,AD]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
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. [S]
Italy's Subterranean Secret: Exploring caves beneath Orvieto in Italy, originally built by the Etruscans long before the Roman Empire. Plus, a former limestone mine under Kansas City. [S,AD]
Subterranean Silo Survival: Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall. Plus, former Atlas missile siloes in Kansas and tunnels hiding under Valetta. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Buried Lab of the Black Hills: Exploring a former gold mine turned scientific laboratory in South Dakota. Plus, limestone tunnels in London and a former water cistern in Denmark. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Mystery of the Kentucky Cave: Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years. [S,AD]
Grand Canyon's Lost Treasure: Exploring inside the Grand Canyon Caverns - North America's largest dry cave system. Plus, Cold War radar bunkers around the UK. [S,AD]
Murder Raid Tunnels: Exploring the extensive air raid tunnels hidden beneath Ramsgate. Also, how the former thriving mining town of Butte, Montana repurposed the 10,000 miles of tunnels. [S,AD]
Italy's Subterranean Secret: Exploring caves beneath Orvieto in Italy, originally built by the Etruscans long before the Roman Empire. Plus, a former limestone mine under Kansas City. [S,AD]
Subterranean Silo Survival: Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall. Plus, former Atlas missile siloes in Kansas and tunnels hiding under Valetta. [S,AD]
Buried Lab of the Black Hills: Exploring a former gold mine turned scientific laboratory in South Dakota. Plus, limestone tunnels in London and a former water cistern in Denmark. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Ireland's Underground Alcatraz: Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for over 400 years. Plus, a former submarine base in the fjords of northern Norway. [S,AD]
Medieval Maze of Secrets: Exploring long narrow tunnels beneath Exeter that were built in medieval times to protect the city. Plus, a marble quarry under the pine forests of Vermont. [S,AD]
Ireland's Underground Alcatraz: Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for over 400 years. Plus, a former submarine base in the fjords of northern Norway. [S,AD]
Mystery of the Kentucky Cave: Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years. [S,AD]
Hotel Bunker of the Apocalypse: Exploring the secret, Cold War US government bunker hidden under Greenbrier Hotel, West Virginia; Plus, delve into the depths of a former slate mine in Wales, UK. [S,AD
Mystery of the Kentucky Cave: Exploring the vast 400-mile Mammoth Cave in Kentucky, USA. Plus, a newly constructed opening into a metal mine in Wales - untouched for over 70 years. [S,AD]
Hotel Bunker of the Apocalypse: Exploring the secret, Cold War US government bunker hidden under Greenbrier Hotel, West Virginia; Plus, delve into the depths of a former slate mine in Wales, UK. [S,AD
Cincinnati's Secret Caverns: Exploring the forgotten underworld hiding beneath the streets of Cincinati, USA. Plus, a state-of-the-art Cold War fortress on the shores of Denmark. [S,AD]
Grand Canyon's Lost Treasure: Exploring inside the Grand Canyon Caverns - North America's largest dry cave system. Plus, Cold War radar bunkers around the UK. [S,AD]
Murder Raid Tunnels: Exploring the extensive air raid tunnels hidden beneath Ramsgate. Also, how the former thriving mining town of Butte, Montana repurposed the 10,000 miles of tunnels. [S,AD]
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. [S]