A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

This historic black and white monastery is one of Bulgaria's architectural jewels.

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

This monumental fountain has moved around the city multiple times.

A popular legend claims that the famous pizza was invented at a restaurant in this alley.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

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

A deep mark on the remains of a Roman temple, believed to be left by a legendary warrior.

Its interior is adorned with some of the best examples of early Christian mosaics.

This hidden alley near the location of Rome's first theater was the site of a curious miracle.

A rather vulgar example of the transition from Latin to the Italian vernacular.

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

Ancient ruins hidden underneath a modern luxury hotel.

One of the most important yet well-hidden museums dedicated to the history of medicine.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

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.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

One of seven Jewish catacombs in Rome and one of only two open to the public.

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