These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A tiny church on a man-made island in the Adriatic.

Northern Ireland's Brobdingnagian stepping stones.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

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

Gods clash with machines in a power plant regenerated as a museum.

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

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

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

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

A Nesting Doll of Churches.

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

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

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

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

The underground sanctuary of a mysterious ancient cult.

The final resting place of the poets Shelley and Keats.

A fairy tale castle in modern Rome.

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

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

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