Where Aleister Crowley taught magick in "La Chambre Des Cauchemars," his "Chamber of Nightmares."

The glowing blue Nymphaeum of Emperor Tiberius.

This massive subterranean fissure is known as the "underground Grand Canyon."

A miniature train-ride through Slovenia's largest cave system.

Two massive boulders, rocking back and forth with the ebbing of the sea.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

This fantastical waterfall is hidden in a cave located in a cracked cliff.

Malaysia's floating mosque.

British Empire's last territorial expansion, claimed by four countries.

This tiny island is home to the world's largest colony of Northern gannets.

This enchanting hill is home to fairy lore and a sinister local mystery.

Every birth, death, and marriage is recorded in these color-coded leather-bound books.

A nuclear bunker built to shelter the politicians and important people of Scotland in case of nuclear attack.

The discovery of this Neolithic settlement, which contained a Stone Age "cathedral," threw archaeologists for a loop.

One man spent 10 years building a spectacular section of road because no one else would.

The 16th-century church has the only stained glass windows that survived the Scottish Reformation intact.

An optical Illusion once believed to be an electrical phenomenon.

A library where thousands of books explain how to avoid another Great Recession.

Even after the church tried to wipe the practice out, this pagan festival lives on each year in a small Scottish village.

During this Shetland Islands celebration, hundreds of torch-carrying "guizers" lead a procession to burn a viking longboat.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

This tiny little cave was said to have been a refuge for a saint with a glowing arm.

Long abandoned underground complex to keep royals safe from a nuclear war that never came.