Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

A blooming house of worship for the masses.

Sacred Indian temple that’s all monkey business.

The world's second-largest sundial, made entirely out of stone.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

The 953 windows undoubtedly make this the world's most beautiful screened porch.

Geometry and mystery come together in an epic show of octagonal masonry.

Water and windows define this defensive Italian well.

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

These gutted monastery ruins still stand proudly in the middle of the Italian countryside.

The Pope’s secret escape route.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

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

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

This sword isn't waiting for a king to pull it out. It was placed there by a saint.

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

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

Architectureal fantasy quarter of Rome.

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

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