Underground Marvels
Historians, engineers, and experts take a look at the underground structures, systems, and phenomena that exist beneath our feet.
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Ep 1Secrets of the Rock
A hidden, subterranean city built within the Rock of Gibraltar was an immense fortress to control the seas during World War II, and new discoveries reveal the secrets of a long-lost chamber with evidence of high-stakes espionage.
Ep 2Mystery of the Lost Labyrinth
A strange, centuries-old labyrinth built into an abandoned quarry was built by an eccentric millionaire, and no one knows why; but now, a new excavation into this mysterious 9,000-foot tunnel system might finally reveal its dark secrets.
Ep 3Secrets of the Terror Tunnels
A vast system of tunnels built almost three thousand years ago was the site of the greatest battles of antiquity, and these disorienting passages could be the deadliest weapon in war; experts reveal what made this underground world so terrifying.
Ep 4The Renegade's Lair
A strange underground system known as the Black Cave was home to an infamous nobleman on the run from the law; today, experts investigate the secrets he left here to discover new parts of this mysterious network.
Ep 5Cave of the Body Snatchers
An eerie system of underground vaults in Scotland was once the hideout for thieves who stole newly-buried bodies and sold them; today, experts are excavating these rubble-filled caves to reveal the secrets of what these bandits left behind.
Ep 6World's Biggest Labyrinth
The world's biggest labyrinth is a 1,553-mile cave system that's home to some of history's darkest mysteries, and new discoveries at this strange place reveal the long-lost secrets of Nazi occupation, Soviet revolution, and Cold War subterfuge.
Science
US
U&Yesterday
GB
