Underground Marvels

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  • : 21
  • : 2
  • U&Yesterday
  • 22
  • Documentary History

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2x1
Hotel Bunker of the Apocalypse
Episode overview
The top-secret construction of a massive nuclear bunker remained concealed under a palatial West Virginia hotel for decades, and now, experts reveal how this vast subterranean structure .. show full overview
2x2
Mystery of the Kentucky Cave
Episode overview
The longest known cave system in the world spans hundreds of miles beneath the hills of Kentucky, and containing prehistoric artifacts and ancient human remains, experts reveal a subterranean mystery that may have changed the course of U.S. history.
2x3
Cincinnati's Secret Caverns
Episode overview
Deep beneath the streets of Cincinnati lies a network of deserted tunnels and caverns that contain a remarkable history of the city's origins, and now, experts investigate to reveal who built this underground labyrinth and why it was abandoned.
2x4
Buried Lab of the Black Hills
Episode overview
Buried nearly a mile beneath the Black Hills of South Dakota is a cutting-edge laboratory at the forefront of astonishing scientific research; experts reveal advancements engineers achieved more than a century ago that keep it operating today.
2x5
Ireland's Underground Alcatraz
Episode overview
Subterranean military fortresses situated on the southern coast of Ireland have protected against enemy invasion for over 400 years, and now, experts investigate how this powerful stronghold transformed into a brutal and terrifying prison.
2x6
Subterranean Silo Survival
Episode overview
Buried nearly a mile beneath the Black Hills of South Dakota is a cutting-edge laboratory at the forefront of astonishing scientific research; experts reveal advancements engineers achieved more than a century ago that keep it operating today.
2x7
Italy's Subterranean Secret
Episode overview
An unprecedented landslide unveils a hidden world beneath a picturesque town in northern Italy, and now experts investigate this vast network of tunnels and passageways that stretch 300 feet underground to reveal the city's subterranean past.
2x8
Grand Canyons Lost Treasure
Episode overview
Descending more than 200 feet beneath the Arizona bedrock lies the largest dry cave system in North America; experts explore this vast subterranean network to reveal the mysteries and undiscovered treasure that remain hidden within its walls.
2x9
Murder Raid Tunnels
Episode overview
Experts explore an extensive network of tunnels beneath Ramsgate, England.
2x10
Medieval Maze of Secrets
Episode overview
A forgotten world of ancient underground passages and medieval engineering lies hidden beneath the town of Exeter, England; experts investigate and reveal how this ambitious tunnel system was the result of one of the deadliest epidemics in history.

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