Exploring the extensive air raid tunnels hidden beneath Ramsgate.
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All episodes for series 2 of Underground Worlds
Exploring inside the Grand Canyon Caverns - North America's largest dry cave system.
Exploring the forgotten underworld hiding beneath the streets of Cincinati, USA.
Exploring the secret, Cold War US government bunker hidden under Greenbrier Hotel in West Virginia.
Exploring the vast 400-mile Mammoth Cave in Kentucky, USA.
Exploring hidden defences that have kept Cork Harbour, in Ireland, safe for many years.
Exploring tunnels beneath Exeter that were built in medieval times to protect the city.
Exploring a former gold mine turned scientific laboratory in South Dakota.
Exploring old tunnels in an abandoned tin mine beneath the moors of Cornwall.
Exploring the caves beneath the beautiful city of Orvieto in Italy.