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

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The final resting place of the poets Shelley and Keats.

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

The underground sanctuary of a mysterious ancient cult.

The oldest operating pharmacy in the world features 800-year-old recipes.

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

The Pope’s secret escape route.

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

Renaissance villa and gardens complete with a tormented colossus.

Jesus' footprints and the first catacombs in the world.

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

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

These "anatomical machines" are only one of the many strange items in this Italian crypt.

The former home of an Italian artist is now a shrine to his ambitious works.

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

St. Francesca Romana, patron saint of drivers, resides in the church she founded.

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

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

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

Venice's "Island of the Mad."

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

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