One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

An abstract and eyecatching clock/fountain is the centerpiece of this little-known German city.

The first (but not only) upside-down house in Germany.

An elevator into the Baltic Sea.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

Twisted trees shaped by coastal winds make this woodland look like something from a spooky story.

A steam powered train that runs on city streets.

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

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

Wooden pathways run through this rocky landscape, which legend says was created when a dwarven king pulled down his own castle to stop raiding giants.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

Constructed by forced laborers, this submarine pen is now a museum and war memorial.

A German artist built a home and garden filled with whimsical art pieces, like a massive, operational volcano.

This German museum devoted to the simple wonders of salt is actually built over an old saltworks.

This ancient oak tree plays matchmaker for singles willing to branch out from the usual dating scene.

The world's first and only three-segment bascule bridge folds up into the shape of a capital "N" to let boat traffic through.

One of the last remaining railway viaducts equipped with a transporter ferry.

Ample proof that watery ends make for well-preserved, millenia-old mummies.

These hilariously laughing bronze figures lampoon empty promises while encouraging civic engagement.

Search the street for hidden cats, all up to different kinds of mischief.

The original home of the Lego has a huge amusement park dedicated to the iconic plastic toy.

This strategic isle was once swapped between empires and almost entirely destroyed in a bomb explosion.

The only remaining U-boat that is still floating never actually saw any action in World War II.