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

This large, circular tomb is the final resting place of the first emperor of Rome.

This Roman underground canal was the longest tunnel ever built until the late 19th-century.

These artificial caves crafted by ancient Romans were elaborate fish farms for moray eels.

Hidden in a high mountain cave, this hermitage dates back to the ninth century.

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

This medieval Italian town is a sheer (and beautiful) cliffside defense.

A narrow opening between the mountains of the Amalfi Coast creates a scenic hidden beach.

The glowing blue Nymphaeum of Emperor Tiberius.

A massive bridge forms part of an aqueduct that was deemed an architectural wonder of its time.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

This tiny islet has somehow housed an ancient temple, two monasteries, a church, a fortress, and a restaurant.

A submerged archeological park still holds the wonders of a Roman Sodom.

A sulfuric hellscape in southern Italy.

Pompeii's less famous neighbor is still revealing her secrets.

This magical-looking island is notorious for the misfortunes suffered by its owners.

Where Venice's gondolas go for a tune-up.

Armenian monks at an island monastery in the Venetian Lagoon make a rare rose petal jam.

The plague quarantine island home to the alleged "Vampire of Venice."

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

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

The Pope’s secret escape route.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.