Copenhagen's celebrated theme park and gardens.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

This nightmarish children's plaything was left grotesque to help kids conquer their fear.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Catalonia Tradition: Beating the hollow Christmas log until it defecates in your fireplace.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

The celebrated eyesore created by starry-eyed sweethearts.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

This "floating railway" is one of the world's oldest monorail systems.

No need to strap in for a "ride" on this walkable roller coaster.

Twisted buildings adorn the banks of the Rhine river.

This futuristic German television spire is actually the world's largest digital clock.

This striking art museum holds an amazing series of curiosity cabinets.

A place to eat for on-the-run agents and espionage enthusiasts.

Statue dedicated to the star of an old television show.

Complex aquaponics systems allow fish and plants to grow in harmony.

A house and yard adorned with bizarre concrete sculptures in a Milwaukee suburb.