An alien church provides much needed silence in the midst of a Finland shopping center.

A decommissioned submarine base makes a great space for graffiti art.

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

A miniature city, once ruled by the Queen of the Netherlands.

Unique house covered in a nightmarish mural of demons, ghosts and monsters.

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

Naturally formed rock city in Poland.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

A monument to Poland's famous alleged UFO abduction case.

One of the largest amphitheaters in Europe is a former Nazi gathering place that still stands today.

An underground city of salt.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Once known as the Illinois Asylum for the Incurable Insane.

Monument to a suicide protesting the Soviet invasion.

Mysterious Spanish catacombs of unknown origins.

An eccentric collection of antique items shares space with a prop-quality witchcraft museum.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

A Spanish town built into the cliffs.

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

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

This abandoned mansion has a window for every day of the year, and is a temple for ghost hunters.