Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

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

A historic observatory precariously perched at the "Top of Europe."

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

Countless grotesque faces stare out from this eerie Prague art wall.

A house of bones — but nobody is quite sure to whom they belong.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

The personal charnel house of Anton Bruckner.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

France's most famous cemetery, with some of its most curious tombs.

This fairy tale forest hides scenes from some of the more obscure and bizarre Western nursery stories.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

Hiding the longest subterranean river known in the world.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A church of bones, decorated with 40,000 human skeletons.