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

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

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

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

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

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Plaques on its facade commemorate the Tiber's most destructive deluges.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

The mystic whose incorrupt corpse still attracts the faithful.

A statue representing a lost Roman profession that was vandalized for centuries.

A massive marble foot is tucked away in a small alley near the Pantheon.

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

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

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

This ancient Roman arch misled treasure hunters for centuries.

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

A rare example of a medieval house in Rome adorned with a melancholic inscription.

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

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

The underground sanctuary of a mysterious ancient cult.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.