A striking 12th-century-style castle built on the edge of a cliff.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

A museum dedicated to a Cold War era sausage.

Goethe's "Faust" was inspired by these rock formations known as the "Devil's Pulpit" and "Witches' Altar."

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This Nazi-built amphitheater was constructed on a sacred mountain site used by various German cults.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

This "floating railway" is one of the world's oldest monorail systems.

This unique Renaissance castle was turned into a home for Nazi occultism.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

The fairy tale castle of the "fairy-tale king."

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

One part local history, 99 parts gruesome haunted house.

An unusual round church in London with a Templar past.

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

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Walk through Czech history in Prague's largest graveyard.

These fantastically named natural pools look like something out of a Scottish myth.

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