An Italian hillside ghost town.

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

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

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

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

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Venice's "Island of the Mad."

The final resting place of the poets Shelley and Keats.

The glowing blue Nymphaeum of Emperor Tiberius.

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

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Geothermal waterfalls in Tuscany.

Thousands of well-dressed mummies below a monastery.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

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

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

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

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

The Grand Mall in Varna hosts one of the biggest collections of Soviet-era paraphernalia in Bulgaria.

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

This rose and lavender oil distillery still operates as it did more than a century ago.