A beautiful but toxic fountain of mercury.

Giant wind turbine with observation deck at the very top.

This small museum gives visitors a chance to soak up the history of the "sponge capital of the world."

Located inside Hoge Veluwe National Park, this museum began as the private collection of a prominent female art collector.

Somewhere there is a giant who can no longer poop, but now travelers can stay inside his anus.

The Suurhusen church tower in Germany leans over farther than the famous Leaning Tower of Pisa.

Peek through a transparent pyramid and drink in the mountain made of books.

A preserved building where the dead were once watched for signs of life.

A charming flea market shop dedicated to retrofuturistic apparati.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

Walk through spectacular aisles of hanging meat and wagon wheel–sized cheese at the world's largest wholesale food market.

A modern-day Lascaux cave underneath Paris.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

France's national museum of scientific and industrial instruments.

This Parisian café sticks almost exclusively to an ethos of reuse.

A museum of carnival attractions where you are invited to ride the rides.

This massive library holds what was once the largest book collection in the world.

Rotterdammers' dirty minds gave this santa a dirty nickname and cursed it to a life of wandering.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

One of the world's most complex timepieces.

The shape of this old salt factory complex was inspired by the course of the Sun.

A university observatory dome painted to resemble the beloved 'Star Wars' droid.

Now overgrown, these anti-tank barriers from World War II are sometimes called "dragon's teeth."