British documentary series exploring incredible feats of human endeavour underground, revealing what people have built, where they have built it, how and why.
Murder Raid TunnelsExploring 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.
Grand Canyon's Lost Treasure
E2
Grand Canyon's Lost TreasureExploring inside the Grand Canyon Caverns - North America's largest dry cave system. Plus, Cold War radar bunkers around the UK.
Cincinnati's Secret Caverns
E3
Cincinnati's Secret CavernsExploring the forgotten underworld hiding beneath the streets of Cincinati, USA. Plus, a state-of-the-art Cold War fortress on the shores of Denmark.
Hotel Bunker of the Apocalypse
E4
Hotel Bunker of the ApocalypseExploring 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.
Mystery of the Kentucky Cave
E5
Mystery of the Kentucky CaveExploring 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.
Ireland's Underground Alcatraz
E6
Ireland's Underground AlcatrazExploring 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.
Medieval Maze of Secrets
E7
Medieval Maze of SecretsExploring 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.
Buried Lab of the Black Hills
E8
Buried Lab of the Black HillsExploring a former gold mine turned scientific laboratory in South Dakota. Plus, limestone tunnels in London and a former water cistern in Denmark.
Subterranean Silo Survival
E9
Subterranean Silo SurvivalExploring old tunnels in an abandoned tin mine beneath the moors of Cornwall. Plus, former Atlas missile siloes in Kansas and tunnels hiding under Valetta.
Italy's Subterranean Secret
E10
Italy's Subterranean SecretExploring caves beneath Orvieto in Italy, originally built by the Etruscans long before the Roman Empire. Plus, a former limestone mine under Kansas City.
Take Plex everywhere
Watch free anytime, anywhere, on almost any device.
