A forgotten "city of water" underneath the famous Trevi district.

Architectureal fantasy quarter of Rome.

An eerie, little-known Neapolitan museum filled with preserved human remains.

A fascinating assortment of cave dwellings, medieval ruins, and sarcophagi are being devoured by the forest.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

Nestled in the hills of Tuscany are gorgeous, multicolored hot springs.

A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

Artist Diego Morlin's war between the natural and human worlds is a wanderer's delight.

Naturally preserved bodies are eerily staged throughout the crypt in varying poses.

The abandoned ruins of a failed resort hide on this verdant, picture-perfect island.

This seaside Italian village doesn't just look Escher-esque, it actually inspired the mind-bending artist.

A madman's personal garden filled with 1,000 sculpted heads.

The world's oldest surviving anatomical theater, where "the dead are pleased to help the living."

A medieval weapon rumored to have been used by the brilliant poet himself.

These delicate sand pyramids look like naturally occurring gothic spires.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

The skulls and bones of thousands of soldiers line the walls of this small Italian chapel.

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

One of the most important yet well-hidden museums dedicated to the history of medicine.

Medieval torture techniques with a modern conscience.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

One of the largest caves in the world open to the public.