A floating cat sanctuary on an Amsterdam canal.

A plaque bearing the names of those who dedicated themselves to protecting Budapest's Jewish population during World War II.

Crouch down, stretch tall, and be sure to flail your legs to pay homage to the Monty Python classic.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

Atop this former dutch railway office sits an interstellar work of art.

Where royalty waits in the height of luxury.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.

A public urinal so pretty, it was declared a national monument.

Amsterdam's former hotspot for public executions and dissections.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

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

A bridge that has seen many reiterations over its lifetime.

Portraits of musicians line Oude Binnenweg, the jazziest street in the city.

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

A nearly 25-foot concrete sculpture of Sylvette, Picasso's muse.

A scene from one of Hungary's most famous novels.

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.

The figure atop this globe is from a Serbian play about a merchant's travels around the world.

Dedicated to one of the pioneers of Serbian football.

A flamboyant five-story building in Bulgaria resembles a crawling snail.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

The ancient Greek Titan guards this massive dam holding a lightning bolt to symbolize electricity.