Rome's ancient Etruscan rival, now a park full of ruins.

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

If you want to talk to the Pope you will have to stare down this surreal vision of Jesus rising from a nuclear hell.

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

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

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

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

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.

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

Jesus' footprints and the first catacombs in the world.

A fairy tale castle in modern Rome.

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

The final resting place of the poets Shelley and Keats.

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

2300-year-old Roman road connecting the empire.

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.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The underground sanctuary of a mysterious ancient cult.

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

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

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