An ancient burial ground believed to have been used for ritual sacrifice.

Some believe this abandoned Brutalist masterpiece inspired George Lucas's Sandcrawler.

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

Jesus' footprints and the first catacombs in the world.

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

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

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

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

Disturbing works of outsider art, carved from whole logs.

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

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

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

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

An eerie, little-known Neapolitan museum filled with preserved human remains.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Geothermal waterfalls in Tuscany.

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

Rome's semi-secret peephole vista is also a former Crusader stronghold.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

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

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

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

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