Bell tower juts out from a village buried under a lake.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

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

This Tuscan lake hides a 13th century town that is still visible when the water recedes.

An ancient artistic garden parlor full of hidden water wonders.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

An Italian hillside ghost town.

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

Abandoned medieval hill town.

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

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

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

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

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

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

Renaissance villa and gardens complete with a tormented colossus.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Pompeii's less famous neighbor is still revealing her secrets.

A small island less than half a mile from Venice is a forbidden island with a dark and twisted past.

A submerged archeological park still holds the wonders of a Roman Sodom.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.