A fairy tale castle in modern Rome.

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

The glowing blue Nymphaeum of Emperor Tiberius.

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

Venice's "Island of the Mad."

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

Geothermal waterfalls in Tuscany.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

Stalactites and stalagmites in a beautifully lit cave.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Thousands of well-dressed mummies below a monastery.

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

The final resting place of the poets Shelley and Keats.

Renaissance villa and gardens complete with a tormented colossus.

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

Architectural monsters are devouring this palace's every door and window.

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

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

2300-year-old Roman road connecting the empire.

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

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

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

The underground sanctuary of a mysterious ancient cult.

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