"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

The world's most active stratovolcano is almost always erupting.

The Jesus tree of Malta bears a striking resemblance to Christ on the cross.

Italian cave with exceptional acoustics and an unsavory history.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

A map of Italy made entirely of trees.

Water and windows define this defensive Italian well.

A 16th-century horror show built in a lovely Italian garden.

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

Ever hear of the Milazzo Cage?

A collection of objects supposedly singed by the hands of souls in purgatory.

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

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

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

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

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

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

The glowing blue Nymphaeum of Emperor Tiberius.

Erotic art covers the walls of the largest ancient pleasure palace.