A shrine of fire worship built on top of a natural flame.

Home to nearly a third of the world's mud volcanoes, Azerbaijan is home to a messy, bubbling, and sometimes explosive landscape.

Mysterious hillside with a continuously burning natural fire.

A gigantic collection of teeny, tiny books.

These Stalin-era industrial 'death traps' hang lifeless above the city

The charmingly disheveled clock tower of Tbilisi's puppet theater.

Small church on top of a huge rock column.

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

Real bones which are said to have belonged to a Polish dragon.

An underground city of salt.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

The "dragon babies" of southeastern Europe.

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

A miniature train-ride through Slovenia's largest cave system.

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

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

It houses the remains of a 17th-century version of the Titanic.

Eight naturally mummified bodies in glass coffins are housed in an underground crypt.

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.