Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The celebrated eyesore created by starry-eyed sweethearts.

The video game-themed street art first popped up in the French city.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

An old department store turned Nazi prison turned artist commune.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A fascinating insight into daily life in the Eastern Bloc.

Where once there was a train station bathroom, there is now this German burger joint.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

This 19th-century fountain's namesake animal isn't what you think it is.

Giant topiary dog once played a role in a terrorist bomb plot.

A large collection of ancient runestones decorates this university courtyard.

A nightly tradition fills the streets of Flogsta with a collective scream.

The official meeting point for the oddly named governing assembly of ancient Sweden.

Ancient burial grounds of the wealthy.

One man's fascination with Turkey led to this backyard mini-city.

A reproduction of a mysteriously preserved body found in the 18th-century and put on display for years before burial.

A centuries-old copper mine that once provided two thirds of the world's copper supply.