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

Secret refuge and museum of the Duke of Florence.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

100 year tradition of fist fights, marked by marble footsteps.

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

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

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

Medieval torture techniques with a modern conscience.

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

The astonishing collection of an infamous criminologist.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

A Nesting Doll of Churches.

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

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

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

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

A fairy tale castle in modern Rome.

A collection of objects supposedly singed by the hands of souls in purgatory.

The final resting place of the poets Shelley and Keats.

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

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

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

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

2300-year-old Roman road connecting the empire.