This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

A petite castle folly in the English countryside.

A castle perched precariously over the Crimean Sea.

Moorish signal station on a stratgic rocky outcrop.

An abandoned castle owned and ignored by Masons carries a cursed history.

This one-time health resort was used by aristocrats around the world.

The one-time stronghold of the noble Douglas family, now home to ghost sightings and nesting birds.

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

Mining town from the late 1890s, once home to Calamity Jane.

A mysterious castle built as a monument to lost love.

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

An eccentric inventor's castle home with its own indoor weather system.

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

A fantastic castle rumored to be the birthplace of King Arthur.

Ruined castle with subterranean vaulted Goblin Ha' or "Goblin Hall."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

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

This Gothic Revival castle used as a shooting location for "The Secret Garden" and other films.

A monolithic monument in Greater London.

The Last Home of an Executed King.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

A 140-year-old castle with underground caves hidden in San Francisco.

An abandoned Jazz Age dream home and con man's hideout in Death Valley.

This stately estate house features a tower covered in a bright, modern mural.