One man's hand-sculpted collection of colorful masks representing a host of gruesome spirits.

A self built castle built by a salt worker in Brazil.

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

Beijing's expansive subterranean hiding spot now crumbles away as a tourist destination.

Nestled in the mountains of Portugal is a tiny village made almost entirely of schist.

Hundreds of caves once used to store grains and animal feed.

Disturbing winged beings decorate the walls of this strange abandoned hermitage.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

A mysterious structure left behind on the Polish mountainside, sometimes called "Hitler's Stonehenge".

The extensive relics of an ancient Roman and Phoenician fish processing plant hide in a town park.

An ethereal glowing blue ocean cave in Croatia.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

Cursed swimming pool left abandoned is now a favorite of filmmakers and ghost hunters.

This imposing modern citadel started out as a home renovation project.

Mysterious face-like images that appeared within an Andalusian house are surrounded by legends of the paranormal.

This indoor ski resort has a mountain contained inside a mall.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

This semi-secret storybook hedge maze is also the oldest garden in the city.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This enormous censer uses a pulley system installed over 400 years ago.

An archeological treasure trove stumbled upon by a couple of children.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

This enchanting hamlet carved into the rock looks like something straight out of Tolkien's Rivendell.