Site of the first radio and telephone broadcasting companies in Copenhagen.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Once a meeting point for great thinkers, and the midpoint of the country.

This bridge's unique architecture honors nautical heritage and encourages self-awareness.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

The world's first combination ski slope and power plant.

Beneath Denmark's Højbro bridge, a bronze merman and his seven sons forever mourn for the mother and wife who left them for land.

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

A massive marble foot is tucked away in a small alley near the Pantheon.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

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

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

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

The remains of this 2nd-century Roman temple are incorporated into a modern building.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

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

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.