A formerly abandoned mental institute, now back in business.

Venice's "Island of the Mad."

Law-protected wreckage serves as a peculiar memorial for an almost forgotten World War II tragedy.

Forgotten German bunkers in China create a sharp cultural contrast.

This abandoned naval battery stood at the ready as recently as the 1980s.

A submerged village appears when dam levels drop.

One of the oldest reform schools in the United States, home to wayward boys such as Merle Haggard, now abandoned.

The Yonaguni Monument, a natural formation or the Japanese Atlantis?

Secret North Korean passage discovered below the world's most dangerous border.

Even King Tut was intrigued by the glass of the Great Sand Sea.

The final resting place of the great navigator, or maybe his brother.

The third largest ship breaking yard in the world has created an eerie shipping graveyard in southern Pakistan.

The abandoned Japanese amusement park once loomed as a dystopian Disneyland.

An ancient city exhumed from the depths of the ocean.

The Los Angeles flood disaster that took 400 lives and ended the career of William Mulholland.

Secluded amid upstate New York’s Adirondack Mountains lies this subterranean emblem of a nation on the brink of nuclear war. And it's for sale.

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

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.