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.

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

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

A Nesting Doll of Churches.

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

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

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.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

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.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

A marine aquarium with an astounding variety of fish hides in the basement beneath the famous Palm House.

A masterpiece of Art Deco architecture hidden in plain sight in West London.

An ornate and disused early 20th-century building has been given new life as a fully operational structure, complete with offices, oyster bar, and a furniture retailer.

The beloved beast's taxidermy remains sit in the Natural History Museum's cafe.

According to legend, this tomb holds the secrets to time travel.

The Great Fire of London and the regulation of one-way streets both started in this alley.