Hidden beneath the streets of London is a secret subway that only carried mail.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

The final resting place for the remains of 143 Habsburg royalty.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

Salt cured mummies continue to turn up in this Iranian mine.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A fiery crater has been burning in the Karakum Desert since 1971.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

An ancient rock engraving shows Aboriginals used their advanced knowledge of the stars to hunt and gather.

This Queens hospital has stood abandoned for almost 20 years after its patients were secretly relocated in the dead of night.

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.

This empty Victorian manse on Staten Island is said to be haunted but is actually a real life crime scene.

Try not to get lost in this picturesque Brazilian labyrinth of the dead.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

A Turkish ghost town abandoned in a population exchange with Greece.

An odd, ancient window that may have once been part of a brutal prison is embedded in the side of New York's Police Plaza.