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

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

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

A Netherlands hotel where you can sleep inside a wine barrel.

This fairy tale forest hides scenes from some of the more obscure and bizarre Western nursery stories.

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

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

This historic Dutch newspaper building is covered with media-themed details—and one unrelated oddity.

Colorful and chaotic stacked hotel in North Holland.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This unattributed sculpture in Amsterdam is hiding in plain sight.

A floating cat sanctuary on an Amsterdam canal.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

A beautifully eclectic mix of architectural styles.

Most prolific publishing house in the 1600s open to the public.

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

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

Each time a baby is born in Ghent, these streetlights flash in silent celebration.

A Museum of Psychiatry in a still-operating mental institution.

The world's largest squirrel statue clutches a pecan bigger than your head.

Bohemian paradise covered in majestic forests.

Double spiral staircases are not unheard of, but they are very rare.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.