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

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

An alchemist's "magic door" stands in the middle of a Roman park.

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

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

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

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The mystic whose incorrupt corpse still attracts the faithful.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

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

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

Gods clash with machines in a power plant regenerated as a museum.

A modern sliver of architecture in Roma.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

This delightful little museum is dedicated to only one thing: pasta.

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

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

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

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

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

Architectural monsters are devouring this palace's every door and window.

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