A purr-fectly spirited bronze celebration of local street felines through history.

This German monument honors the so-called "Prince of Mathematicians."

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

Eight naturally mummified bodies in glass coffins are housed in an underground crypt.

A spitting ode to a German serial killer.

One of the oldest wine cellars in Germany is now a restaurant beneath Bremen's town hall.

A stunning gilt bronze relief denounced by Hitler as "degenerate art"—even though it was dedicated to the Nazi leader.

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.

One room inside this building mesmerizes all with its parabolic dome.

The only microgravity tower in Europe can produce nine seconds of weightlessness.

This red light district plaza memorializes the Fab Four and their historic connection to the area.

Hamburgers are intensely proud of their tunnel beneath the river.

Hidden in plain sight on a gable between two towers on the roof of shipping firm F. Laeisz' headquarter in Hamburg sits an unexpected bronze sculpture.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

Model Trains and Much More in Hamburg.

In the heart of Luxembourg's "little Switzerland" weaves a breathtaking natural sandstone canyon with a mythological past.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

This unique architectural wonder is also tied to one of the 20th-century's most renowned writers.

This museum documents the ancient practice of salt production in Figueira da Foz.

These 400-year-old ruins are all that's left of the monastery where Ines de Castro was assassinated by the King of Portugal.

One of the largest Roman settlements in Portugal.

One man's remarkable private collection of art from around the world.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.