Amsterdam's Red Light District leaves little to the imagination.

This unattributed sculpture in Amsterdam is hiding in plain sight.

A beautifully eclectic mix of architectural styles.

Established in 1638 to battle the Black Death, Hortus Botanicus Amsterdam is a treasure trove of rare flora.

Each spring, a dreamlike carpet of bluebells overtakes the forest floor.

Devious political maneuvering and four ancient, working telescopes are central to the world's second-oldest observatory.

Somewhere there is a giant who can no longer poop, but now travelers can stay inside his anus.

This ghost town in Belgium will lose its street art when it ceases to exist.

Ancient man-made caves underneath small town Belgium.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

An open-air sewer system that was covered piece-by-piece over 300 years.

Hiding the longest subterranean river known in the world.

Part modern art project, part traditional chapel, this see-through church is only substantial from the right angle.

Incredible labyrinth of man made caves.

The world's biggest pet store.

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

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

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

This German art chapel is perfect for those who like their worship hard, modern, and utterly alien.

Twisted buildings adorn the banks of the Rhine river.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

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