In a remote Louisiana swamp, the ruins of a massive industrial operation suggest that something evil once happened here, and new discoveries at this eerie site reveal what these abandoned buildings were for and why they were deserted.

An abandoned industrial complex by Lake Michigan was once a top-secret military compound that protected America from enemy attacks; new discoveries reveal what really happened here and why the government turned its back on this juggernaut.

An island of dense jungle is home to an abandoned complex with a dark past of bloodshed and rebellion, and new discoveries at this deserted place reveal why it was built and the gruesome circumstances of its downfall.

A strange bunker near the Kennedy Space Center once served a top-secret military function should doomsday ever come to the Sunshine State; experts use declassified intel to reveal the sinister purpose of this forbidding facility and why it was abandoned.

An abandoned castle is the site of hundreds of horrific murders perpetrated by the mysterious countess who once lived there, a woman alleged to be one of the most prolific killers in history; new discoveries reveal what really happened here.

Abandoned towers in southern Greece are the ruins of a fearsome warrior civilization descended from the Spartans, and new discoveries reveal the role these towers played during generations of violent blood feuds among the clans that lived here.

A massive, alien-like fortress built into a mountainside is the central node to a network of pipelines that race outwards like tentacles; behind-the-scenes access reveals the secrets of why this strange complex was built and why it was abandoned.

The ruins of an abandoned prison are evidence of a chaotic riot that put the prisoners in charge; special access to its burnt-out interior reveal how inmates took over Ireland's Alcatraz and why it is deserted today.

An eerie set of buildings in Paris is evidence of an unspeakable evil; new discoveries reveal the horrific things that happened here, and why they were abandoned.

A strange bunker in a treacherous landscape once belonged a notorious dictator who's paranoid fantasies drove bizarre and elaborate feats of engineering; new discoveries reveal the secrets of these structures and why the nightmares that built them.