A fairy tale castle in modern Rome.

The glowing blue Nymphaeum of Emperor Tiberius.

Jesus' footprints and the first catacombs in the world.

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

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

Venice's "Island of the Mad."

Geothermal waterfalls in Tuscany.

Thousands of well-dressed mummies below a monastery.

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

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

Stalactites and stalagmites in a beautifully lit cave.

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.

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

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

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

Renaissance villa and gardens complete with a tormented colossus.

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

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

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

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

The underground sanctuary of a mysterious ancient cult.

This community on a small Venetian island has taken to painting their houses in bright neon hues.