One of the largest caves in the world open to the public.

Medieval torture techniques with a modern conscience.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

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

The astonishing collection of an infamous criminologist.

Dramatic sea stacks adorn the coast of this small village on the Adriatic coast.

Walk through a fairytale in Tuscany.

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

An ancient artistic garden parlor full of hidden water wonders.

Venice's island of the dead.

This Tuscan lake hides a 13th century town that is still visible when the water recedes.

This half-finished "city of toys" was almost Italy's own Las Vegas.

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

This picturesque Umbrian city has a subterranean side that has long remained hidden.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

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

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

A sunken idol welcomes parishioners to Davy Jones' Locker.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

The remains of a town so thoroughly destroyed by French forces that the citizens simply left.

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

Virgil's many-mouthed gateway to the underworld.