Pilgrimage site for star-crossed lovers.

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

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

Twisted buildings adorn the banks of the Rhine river.

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

This former steel and coal plant is now a neon-lit industrial fantasia.

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

The Bauhaus-style former industrial complex is considered the world's most beautiful coal mine.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

An industrial relic is now one of Europe's most staggering art spaces.

When this funny little building went up in the 19th century, most people thought it would simply fall over.

Five candy-colored villages on the Italian Riviera.

A beautiful discovery site of prehistoric burials.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

What if all public housing projects had been designed by "the Pygmalion of modern architecture," not only their prototype?

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.

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

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

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

This funky former tobacco factory is one of the most striking examples of Madrid's cultural diversity.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.