An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This 19th century cyclorama acts like an analogue time machine to a different era.

A spherical "micro-nation" in the heart of Vienna.

The world's biggest pet store.

This monolithic slab of art metal crowns a German slag heap.

The monumental home of Prussia’s eccentric "Cannon King."

The Bauhaus-style former industrial complex is considered the world's most beautiful coal mine.

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”

Walk inside a half mile long crevice right outside the town of Garmisch Partenkirchen.

This 600-year-old home seems to defy physics.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

The last bastion of Roman presence north of the Alps looms over a German town.

This futuristic German television spire is actually the world's largest digital clock.

A varied collection of brains in alcohol.

An abandoned underground bathroom is now a space for public art.

Twisted buildings adorn the banks of the Rhine river.

A 12th-century fortress containing some of Berlin's oldest buildings.

Residing along a busy thoroughfare, this sculpture urges passersby to consider the future.

This small condiment museum makes all manner of mustards with a 200-year-old mill.

The body of at least one victim of a construction accident was left behind in the collapsed pylon, buried under tons of concrete.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.