Visit the ancient, mysterious Roman catacombs ... in the Netherlands.

This neighborhood of futuristic ball houses looks like an alien settlement in a science fiction film.

A late-medieval Dutch castle with trick fountains in its whimsical water gardens.

A seven-century-old jail tells a not-so-pleasant history of crime and punishment.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

The tallest waterfall in the Netherlands is a lovely, stepped feature that is only 50 feet tall.

It appears as if a man is standing behind this giant airport clock, painting the hands in real time.

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

A dream-like maze full of strange art, surreal spaces, and fantasy landscapes to get lost in.

Incredible labyrinth of man made caves.

Rich with fauna and flora, nature-lovers can walk across the sea at this UNESCO World Heritage spot.

Take a stroll through the hellish grotesques of Hieronymus Bosch in this elaborate Netherlands church.

A true Valhalla for cactus and succulent lovers.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

A market built atop boats is one of the few floating holiday markets in Europe.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

A former plague hospital turned medical museum.

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

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

This subterranean studio is filled with fascinating kinetic art.

Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

An overgrown and largely forgotten cemetery lies hidden within the outskirts of Amsterdam.

A Portuguese Jewish cemetery filled with stunning grave monuments that date back to 1614.