A self-built mosaic house and sculpture park.

World's first "penitentiary," meant to be humane, drove men insane.

Venice's "Island of the Mad."

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

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

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

This grave resides at the crossroad of three parishes.

This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".

This South London cemetery holds the remains of more than 15,000 people.

Submerged busts of communist and socialist figures from the USSR.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

An artist's mausoleum with a haunting echo.

Now a pile of ruins and rubble, this was a lovely mountain town as recently as 1960.

Siberian ghost town built by gulag prisoners.

This attraction was abandoned after the Chernobyl disaster.

Haunting monument to the German Jewish philosopher who died while fleeing fascism.

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

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

A bizarre house filled with an astounding array of collections.

If there is one thing you don't want to be in Sweden during Christmas, it's a Yule Goat.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.