A mysterious American pyramid built out of Cold War paranoia, a haunted prison, and a cluster of structures in the Atlantic are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

Traces of a Russian hole to hell in the Arctic, a military base in America's wild west, and a strange looming tower are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

A secret Russian military base in the Gobi Desert, a strange complex in an American wasteland, and a relic high atop a mountain are mysterious deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

A secret structure on a sinister mountain, an industrial compound swallowed by a forest, and a mysterious run in a sand dune are strange deserted engineering projects, and new discoveries reveal how they were built and why they were abandoned.

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.

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; 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 snow-capped 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.

A haunted lighthouse on Lake Michigan, a town where everyone seems to have vanished all at once, and a secret complex of tunnels beneath London are deserted engineering projects.

New discoveries reveal how an unfinished Nazi fortress was built.

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.

An alien Stonehenge with a sinister purpose, an eerie building filled with strange labyrinths, and an endless concrete track in the middle of nowhere are deserted engineering projects, and new discoveries reveal why they were abandoned.

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

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

A one-time fairytale castle is rumored to be haunted; experts investigate the secrets and ghostly stories of this eerie fortress.

A mysterious town in South Africa is deserted, even though it was once a booming community; experts reveal the cataclysm that caused the people of this once-prosperous town to suddenly leave and never come back.

On a desolate island near Greece, abandoned buildings are evidence of a group of people that were forbidden to leave; experts reveal who was forced to stay here and if there was a cover-up to conceal what really happened at this strange place.

A vast network of subterranean bunkers in the American west was home to the power to destroy nations, but today, this facility is deserted, and new discoveries reveal why this eerie place was built and why it was abandoned.

A haunted prison with a terrifying past once housed America's most notorious criminals, but today, the fortress stands in ruin, and experts reveal evidence of ghostly secrets hidden in the crumbling jailhouse walls.

An abandoned system of caves was once the meeting place of a secret society that worshiped Satan and performed black magic, and new discoveries at this mysterious site reveal what really happened here and why a Founding Father was a frequent guest.