A strange alien shrine on a mountain peak, a bridge built in the Alaskan wilderness, and an American castle with a dangerous secret are mysterious deserted engineering projects. New discoveries reveal how they were built and why they were abandoned.

An American ghost town in the Amazon jungle, a secret Nazi base, and a deadly concrete fortress 866 miles long are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

A terrifying sea fortress, a highway in the Amazon that suddenly vanishes, a mysterious structure in the shadow of the Statue of Liberty are deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

Go inside the abandoned city of Chernobyl to follow an investigation into the truth behind the nuclear meltdown there over 30 years ago. New evidence reveals that this accident may be one of the greatest sabotages in history.

Eerie ghost ships stranded in an alien desert, sinister ruins known as the Dragon's Teeth, and a ghostly complex with a bloody past are deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

A ghost ship thousands of miles away from where anyone expected, a bridge to nowhere in Florida's Hurricane Alley, and a haunting mountain complex with a bloody secret are deserted engineering projects. New discoveries reveal why they were abandoned.

An alien Nazi structure that changed history, a strange Soviet monolith known as the Tower of Death, and a concrete ocean giant are deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

An entrance to the underworld in the American wild, a haunting Soviet underwater prison, and a strange complex of towers in a forest of ice are deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

A strange deserted city in America's heartland, an eerie gigantic wall deep in snowcapped mountains, and a mysterious top-secret Soviet facility are deserted engineering projects. New discoveries reveal how they were built & why they were abandoned.

A deserted town in Spain with a bloody past and a ghost fleet heading nowhere are homes to dark American secrets, and new discoveries reveal how they were built and why they were abandoned.

Discoveries reveal why a complex of tunnels beneath London are abandoned.

An eerie prison with a dark past that became the setting of an iconic Hollywood movie and alien monoliths on a strange and remote island are deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

New discoveries reveal why a sinister alien Stonehenge is abandoned.

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.