Underground Marvels

Experts reveal how a nuclear bunker was concealed under a palatial hotel.

Experts unearth a mystery from the longest known cave system in the world.

Experts investigate deserted caverns beneath the streets of Cincinnati.

Experts investigate a cutting-edge underground laboratory in South Dakota.

Experts reveal how an Irish military fortress transformed into a prison.

A decommissioned missile launch facility in Kansas remained one of the best kept subterranean military secrets of the Cold War, and now, experts reveal how this abandoned underground complex transformed into a state-of-the-art survival bunker.

Experts explore a subterranean world discovered beneath an Italian city.

Experts explore the largest dry cave system in North America.

Hidden beneath the town of Ramsgate, England, lies a hidden network of over three miles of air raid tunnels; experts investigate and uncover an extensive WWII bomb shelter that became a permanent refuge for many civilians after a devastating attack.

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.