This monolithic slab of art metal crowns a German slag heap.

Twisted buildings adorn the banks of the Rhine river.

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

The struggle of a small Dutch island against the sea.

This former hydraulic laboratory is now a woodland dotted with old engineering models.

The 20-mile causeway that separates the Netherlands from the sea.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

The world's largest bicycle shelter can hold more than 12,500 two-wheelers.

This large sand dune in the Netherlands is home to wind-whipped trees with "floating" roots.

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

The tallest mountain in mainland Netherlands isn't actually very tall.

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.

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

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

A monument to the thousands of Canadian soldiers who died capturing the French ridge during World War I.

The world's tallest boat lift stands as a massive piece of industrial tourism.

The "stairway to heaven" lookout tower was built to resist weather, arson, and the laws of physics.

A maze of crosses marks the jumbled divide between the Netherlands and Belgium.

Invisible bridge parts the waters, invoking biblical images and preserving the ominous feel of an ancient moat.

A miniature city, once ruled by the Queen of the Netherlands.

A large measuring stick marks the lowest point of a country that is partially under sea level.

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

A true Valhalla for cactus and succulent lovers.