Iconic pyramid from famed British architect Norman Foster designed to represent all of the world's religious faiths.

An entertainment center in a huge transparent tent.

One of the largest caves in the world open to the public.

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

This massive subterranean fissure is known as the "underground Grand Canyon."

These pools have been abandoned for over 20 years.

Located right outside of Vienna, visitors can take in expansive views of an ethereal forest.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

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

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

Two monstrous faces loom over a village in Czechia.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Europe's second largest ossuary wasn't discovered until 2001.

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

Bohemian paradise covered in majestic forests.

This former quarry is now a picturesque gorge that hides a sunken lake.

An old asylum graveyard that's been abandoned for half a century attracts those seeking a dark thrill.

An Orwellian sculpture with eyeball cameras watches passersby.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

A sculpture of the iconic East German car on four legs is a tribute to those who traveled to Prague seeking asylum.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

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

The hidden lair of an alchemist rediscovered in a 2002 flood.