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

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

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

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

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

This large, circular tomb is the final resting place of the first emperor of Rome.

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

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

The Pope’s secret escape route.

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

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

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

A forgotten "city of water" underneath the famous Trevi district.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.

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

A fairy tale castle in modern Rome.

Jesus' footprints and the first catacombs in the world.

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

2300-year-old Roman road connecting the empire.

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

The underground sanctuary of a mysterious ancient cult.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Architectureal fantasy quarter of Rome.

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