Virgil's many-mouthed gateway to the underworld.

Medieval town turned hippie commune, once home to the secret foreskin of Jesus Christ.

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

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

This immaculate and historic water garden culminates in a massive stone dining table with an inset fountain for chilling the wine of the Cardinal's guests.

2300-year-old Roman road connecting the empire.

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

An Italian hillside ghost town.

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

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

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

The underground sanctuary of a mysterious ancient cult.

Geothermal waterfalls in Tuscany.

This 16th-century monastery has been turned into a surrealist architecture compound.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Architectureal fantasy quarter of Rome.

Thousands of well-dressed mummies below a monastery.

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

A 16th-century horror show built in a lovely Italian garden.

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

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.