An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Two stunning 17th-century libraries and a cabinet of curiosities.

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

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

Of course Salvador Dalí lived in a castle...

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

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

This ancient Spanish castle sits high upon a hilltop.

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

A harem-inspired Moorish fantasy design in a Victorian-era Welsh castle.

Abandoned castle was once a grand example of Russian privilege, built exclusively to win a frivolous bet between noblemen.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

Recently restored menagerie of Victorian-era beasts.

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

A ruined castle has more than its fair share of legends and ghost stories.

360° views of the city plus five floors of optical illusions and hands-on science.

The final resting place of soldiers' loyal canine companions.

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

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

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

Geometry and mystery come together in an epic show of octagonal masonry.

This Mediterranean castle was built for a millionaire and his giant dog.

A castle built for love, and abandoned due to heartbreak.

A sculptor's dream castle turned fantastical ruin.