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

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

This monumental work of art symbolizes the coming together of a previously divided city.

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

Cold war icon and onetime "hole" in the iron curtain.

A monument to the man who almost killed Hitler.

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

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

A fascinating insight into daily life in the Eastern Bloc.

At the base of this tower, a plaque marks the original center point of the Netherlands.

This unassuming bridge is most likely one of Michelangelo's unfinished masterworks.

This ancient Roman arch misled treasure hunters for centuries.

This curious, round temple is the oldest still-standing marble building in Rome.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

A little sculpture with a large wardrobe.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Architectural monsters are devouring this palace's every door and window.

Rome’s legendary peephole vista is also a former Crusader stronghold.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

These giant yellow bowling pins seem to be defying gravity.