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

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

A huge enchanting public park just outside the ancient walls of Rome.

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

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

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

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

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

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

A Nesting Doll of Churches.

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

Jesus' footprints and the first catacombs in the world.

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.

2300-year-old Roman road connecting the empire.

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

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

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

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

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

Architectureal fantasy quarter of Rome.

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

An architectural oddity hides in plain sight on this iconic London bridge.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.