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

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Incredible labyrinth of man made caves.

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

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

A distinctive former power plant turned university lecture hall looks like it could make you breakfast.

Collection of fossils, plants, and ancient animals encased in amber.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

Christ's blood preserved in a Belgian town.

A little sculpture with a large wardrobe.

Be(w)ar(e) the moat around this historic Czech castle.

The "dragon babies" of southeastern Europe.

A miniature train-ride through Slovenia's largest cave system.

This one-time health resort was used by aristocrats around the world.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

An old slave lookout in Cuba's historic sugar cane fields.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

This island hill is strewn with boulders carved by shipwreck victims from the age of sail.

The largest Chinese cemetery in the world outside of China dates back to the 15th century.

Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Baroque celebration of the end of the Great Plague of Vienna.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.