The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

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

Overlooked amid the tourist bustle of Florence, this museum is dedicated to the craft of stone inlay.

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

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

Secret refuge and museum of the Duke of Florence.

The astonishing collection of an infamous criminologist.

Crushed coral and crystals give the sand its signature coloration.

David Sedaris called it "The greatest shop in the world."

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

Abandoned medieval hill town.

A collection of objects supposedly singed by the hands of souls in purgatory.

Jesus' footprints and the first catacombs in the world.

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

The final resting place of the poets Shelley and Keats.

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

Thousands of well-dressed mummies below a monastery.

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

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