A Nesting Doll of Churches.

A 15th-century monumental Latin inscription on this house celebrates Lorenzo Manilio's love for Rome.

An ancient Egyptian obelisk is now used to commemorate fallen Italian soldiers.

Plaques on its facade commemorate the Tiber's most destructive deluges.

A colossal aqueduct from the second century B.C., deeply hidden in a gorge on the outskirts of Rome.

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

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

An enigmatic modern marker left next to a historic Roman site.

This medieval church in Rome was almost destroyed following a terrorist attack in 1993.

An 18th-century post box used to alert the church of sick and ailing foreign pilgrims.

A fortified medieval basilica on the Caelian Hill preserves extraordinary frescoes and one of Rome's most beautiful hidden cloisters.

Romans decided this 16th-century "talking statue" was so ugly, they named it after a primate.

This ancient market is often referred to as the oldest shopping mall in the world.

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

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

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

The Pope’s secret escape route.

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

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

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

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

This curious, round temple is the oldest still-standing marble building in Rome.

This statue is the only female representation of Rome's "talking statues."

Known for centuries as the famous Roman emperor's burial place, this monument is actually something else.