This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

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

Ancient ruins hidden underneath a modern luxury hotel.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

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

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.

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

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

One of the most important yet well-hidden museums dedicated to the history of medicine.

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

The Pope’s secret escape route.

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.

Jesus' footprints and the first catacombs in the world.

A fairy tale castle in modern Rome.

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

The final resting place of the poets Shelley and Keats.

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

The underground sanctuary of a mysterious ancient cult.

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

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

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

Architectureal fantasy quarter of Rome.