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

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

Abandoned medieval hill town.

Five candy-colored villages on the Italian Riviera.

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

Ruins of a 10th century church tucked away deep in a botanical garden.

This 16th-century monastery has been turned into a surrealist architecture compound.

An Italian hillside ghost town.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

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

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

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

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Venice's "Island of the Mad."

The oldest operating pharmacy in the world features 800-year-old recipes.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

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

Architectureal fantasy quarter of Rome.

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

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