Underground Marvels

The Maginot Line (1x7)

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Treasures of the Lost Mine Caverns hidden deep inside a remote mountain are home to a precious mineral found nowhere else on earth, and experts and treasure hunters use cutting-edge tech to follow rumors of a mysterious long-lost mine in search of a payday. 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.