Season 2

2022-01-10 · 45m

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.

2022-01-17 · 45m

Exploring inside the Grand Canyon Caverns - North America's largest dry cave system. Plus, Cold War radar bunkers around the UK.

2022-01-24 · 45m

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.

2022-01-31 · 45m

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.

2022-02-07 · 45m

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.

2022-02-14 · 45m

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.

2022-02-21 · 45m

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.

2022-02-28 · 45m

Exploring a former gold mine turned scientific laboratory in South Dakota. Plus, limestone tunnels in London and a former water cistern in Denmark.

2022-03-07 · 45m

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.

2022-03-14 · 45m

Exploring caves beneath Orvieto in Italy, originally built by the Etruscans long before the Roman Empire. Plus, a former limestone mine under Kansas City.