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

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

The walls and streets of the ancient city are peppered with penises.

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

This seaside Italian village doesn't just look Escher-esque, it actually inspired the mind-bending artist.

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

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

Erotic art covers the walls of the largest ancient pleasure palace.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

Ancient snack bar of the Roman Empire re-opened.

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

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

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

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

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

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

Go inside to really appreciate this 500-year-old technological masterpiece.

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

The underground sanctuary of a mysterious ancient cult.

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

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

The largest known Ancient Egyptian obelisk.