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

Artwork tucked within the trees greets visitors with surreal sonic experiences.

What was once a bustling mining installation is now a bustling hub of contemporary art.

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

Descend into the tunnels to experience the life of a coal miner.

A once-magnificent collegiate church is falling into ruin.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

This abandoned Belgian fortress is purposefully being left to nature.

Sculpture designed by Turkish artist and professor Mehmet Ali Uysal.

This bird-loving brewery is situated in an old municipal bathhouse, nestled beside a 300-year-old windmill.

This pirate-broadcasting-tower-turned-restaurant played a rebellious role in the history of Dutch television.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

Unchanged for centuries, this medieval library keeps its books in chains.

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

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

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

A grassy pyramid named after a French battle.

Watch the local Netherlands birds from inside this giant eco-egg.

The Rozenberg wind wall in South Holland makes for smooth sailing through the Calandbrug canal.

A set of 27 bamboo tubes creates an eerie soundscape that changes with the wind.

Its town washed away centuries ago, this lonely tower by the sea tells the tale of a mermaid and a curse.

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

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

Scale model of St. Peter's Cathedral (Rome) in the middle of a small Dutch town.