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

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

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

Ancient ruins hidden underneath a modern luxury hotel.

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

This ancient market is often referred to as the oldest shopping mall in the world.

A huge enchanting public park just outside the ancient walls of Rome.

A forgotten "city of water" underneath the famous Trevi district.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Architectureal fantasy quarter of Rome.

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

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

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

A plaque on the base of this statue holds a bewitching design.

According to tradition this is the oldest church in Venice, but its actual age is a mystery.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

This statue pays tribute to the iconic musician in the place where he recorded his final studio album.

Watch cheese-flipping robots in action at this factory and museum.

The world's largest second-hand graces a clock surrounded by constantly changing flower beds. 

An opulent monument built for a duke who donated his entire fortune to the city of Geneva.

This colorful but controversial ceiling has been likened to a 21st-century Sistine Chapel.