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

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

An existential riddle in the world's largest ancient castle.

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

A mocking tribute to the past and modern leadership of Prague.

Street artists transformed an abandoned air vent into the beloved Star Wars robot.

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

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

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

A Jenga-style cylindrical tower of books that appears to go on forever.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A whimsical bridge adorned with decorative dragons.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

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

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

Colorful murals by Jean Cocteau hide within this peaceful London sanctuary.

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

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

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

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The narrowest street in Paris.

A modern-day Lascaux cave underneath Paris.

19th century pendulum and a clock restored by a rogue group of guerilla artists.