Secrets of the Terror Tunnels

Some of the world's most incredible engineering projects are now deserted. Revisit a Soviet megastructure, a massive Nazi brainwashing complex, and a dangerous desert pass. How were they built? Why were they mysteriously abandoned?

Some of the world's most incredible engineering projects are now deserted. Explore a ghost town that was once a dangerous industrial hellscape, a giant warship at the bottom of the ocean, and a top secret relic from the Cold War.

The events that took place in a town outside Chernobyl are explored.

The stories behind a massive military site and more are explored.

The world's strangest ghost towns are home to dark secrets, creepy buildings, and eerie sights, and new discoveries reveal why they were abandoned.

On a strange island off the coast of Croatia, the mysterious ruins of a long-abandoned hideout look like they once belonged to a James Bond supervillain, and new discoveries reveal why it was built and why they were abandoned.

The ruins of a once-palatial compound contain the secrets of one of history's most notorious criminals, and new discoveries reveal why this high-security estate was built and why it was abandoned.

Tunnels filled with human bones lie beneath the streets of Paris, and this horrifying engineering marvel points to a dark secret. New discoveries reveal why this grisly underground death maze was built, and why it was abandoned.

A ghost town in the American West was once a Gold Rush hotspot and one of the most violent places in America. Today, there are legends of a secret treasure buried in the surrounding hills, and new discoveries might finally reveal its true location.

In Alaska, the ruins of a massive compound point to eerie evidence of an apocalyptic mystery. New discoveries reveal why this strange marvel was built in the snowy wilds of the Last Frontier and why it was abandoned.

A strange complex of tunnels on the grounds of a bizarre mansion were under lock-and-key for a century. Since its rediscovery, some believe its mysterious place is a gate to hell. New discoveries reveal its secret purpose and why it was abandoned.

Near the destroyed city of Pompeii, an eerie complex of underground tunnels snake beneath a volcano, and some believe these passages were intended as a gateway to hell. New discoveries reveal exactly why they were built and why they were abandoned.

A strange complex of buildings on a remote tropical island was once home to a large seaside community, but today, locals avoid the area and claim that it's haunted. New discoveries reveal why this eerie place was built and why it was abandoned.

At an infamous prison in the Amazon, the most dangerous criminals on earth faced hard labor, a hostile environment, and death by guillotine; today, it's deserted, and new discoveries reveal why this compound was built and why it was abandoned.

An abandoned town in the Nevada desert are the ruins of an American Atlantis, destroyed by catastrophic floods when the Hoover Dam was built; today, experts investigate the secrets of this ghost town as water levels recede and the city reemerges.

A mysterious castle was once a fairytale estate, but today, the building is said to be haunted, and experts investigate the secrets of this eerie fortress and the ghostly stories inside.