Venice's "Island of the Mad."

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

The final resting place of the poets Shelley and Keats.

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.

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.

2300-year-old Roman road connecting the empire.

Thousands of well-dressed mummies below a monastery.

Geothermal waterfalls in Tuscany.

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

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.

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

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

Renaissance villa and gardens complete with a tormented colossus.

The underground sanctuary of a mysterious ancient cult.

The middle finger of modernity.

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

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

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

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