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

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

A sculpture serving as an homage to Pope John Paul II.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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.

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

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

An alchemist's “magic door” stands in the middle of a Roman park.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

Brussels' favorite peeing boy has a sister.

A little sculpture with a large wardrobe.

Meet the bronze beloved pet to a family of famous peeing statues.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

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

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

One of downtown Berlin's last reminders of its Communist past.

A fascinating insight into daily life in the Eastern Bloc.

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

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

This bridge was constructed from the rubble of the infamous Bastille.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.