—Uncovering subterranean phenomena around the globe, their impressive stories, unique origins, essential roles throughout history, and the secrets they keep hidden deep below.

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Season 110 of 10 Episodes

A hidden, subterranean city built within the Rock of Gibraltar is an immense fortress to control the seas during World War II; new discoveries reveal the secrets of a long-lost chamber with evidence of high-stakes espionage.
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.
A vast system of tunnels built almost 3,000 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.
A strange underground system known as the Black Cave is connected to a fairytale castle and was home to an infamous nobleman on the run from the law; experts investigate the secrets he left here to discover new parts of this mysterious network.
Eerie system of underground vaults in Scotland was once hideout for thieves who stole newly-buried bodies and sold them; experts excavate these rubble-filled caves to reveal the secrets of what these bandits left behind.
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.
Caverns hidden deep inside a remote mountain are home to a precious mineral found nowhere else on Earth; experts and treasure hunters use cutting-edge technology to follow rumors of a mysterious long-lost mine in search of a payday.
A labyrinth of vast tunnels in the French countryside has served as a secret hideout during wartime for centuries, and on its walls, experts have discovered the final confessions of soldiers who fought during one of the deadliest days of World War I.
A buried ancient city hidden five-stories underground can house 3,000 people in secret; experts use the latest tech to reveal the truth behind this strange place.
A mysterious cave system is home to some of the oldest human remains ever discovered, and today, the explorers and researchers investigating this site are uncovering shocking evidence of cannibalism among its Ice Age denizens.

A mysterious cave system is home to some of the oldest human remains ever discovered, and today, the explorers and researchers investigating this site are uncovering shocking evidence of cannibalism among its Ice Age denizens.
Upcoming
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.
Upcoming
A strange underground system known as the Black Cave is connected to a fairytale castle and was home to an infamous nobleman on the run from the law; experts investigate the secrets he left here to discover new parts of this mysterious network.
Upcoming
A labyrinth of vast tunnels in the French countryside has served as a secret hideout during wartime for centuries, and on its walls, experts have discovered the final confessions of soldiers who fought during one of the deadliest days of World War I.
Upcoming
A buried ancient city hidden five-stories underground can house 3,000 people in secret; experts use the latest tech to reveal the truth behind this strange place.
Upcoming
A vast system of tunnels built almost 3,000 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.
Upcoming

Uncovering subterranean phenomena around the globe, their impressive stories, unique origins, essential roles throughout history, and the secrets they keep hidden deep below.

Jamie Effros

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Underground Marvels

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6 episodes will be broadcast over the next two weeks

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