Incredible labyrinth of man made caves.

An amusement park on the grounds of an unused nuclear power plant, with a swing ride inside the cooling tower.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

One of the only spherical 19th century gas containers left today.

A beautiful maze marks where three countries meet.

This former Nazi castle was built as a school to train what would have been the future of the Third Reich.

Tucked away in a small German apartment is an eclectic museum devoted to West African vodun culture.

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

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

No need to strap in for a "ride" on this walkable roller coaster.

Geothermal waterfalls in Tuscany.

"Unity, Creativity, Beauty."

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Commonly acknowledged as the only public monument to the Devil himself.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.