Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

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

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

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

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

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.

Natural cathedral designed by Italian artist Giuliano Mauri.

A fairytale island floats in the middle of Italy's little-known Lake Orta.

The secret medieval communication system will whisk your words above the noise of the crowd.

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

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

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

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

Secret refuge and museum of the Duke of Florence.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

Abandoned medieval hill town.

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

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

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

The location of the last witch trials of Italy, known as "The Salem of Europe."

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

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