Stockholm's narrowest alley is barely over two feet wide.

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

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

A collection of modern and vintage pinball machines housed in the cellar of a 15th-century building.

A collection of old neon signs from all over Poland line a secluded courtyard.

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

The giant statue and its model solar system honor the native Pole who declared that the Earth revolves around the Sun.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

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

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

A marvel of Byzantine engineering under the streets of Istanbul.

Where commuters walk through remnants of an ancient Greek necropolis.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The most famous location in China was home to whole dynasties worth of imperial rulers.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

Not quite the menace it once was, this monster still has some chops.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

An ancient capital city that dates back 3,000 years and harbors many surprises.

A "miracle" that seems to produce more holy fistfights than holy revelations.

Two stone columns flank the grand Venice square, but there were supposed to be three.

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.