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

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

An ancient artistic garden parlor full of hidden water wonders.

The location of the last witch trials of Italy, known as "The Salem of Europe."

Eighteen mummies have stood guard behind the altar of this tiny church since 1833.

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

Bell tower juts out from a village buried under a lake.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

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

A Nesting Doll of Churches.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

Jesus' footprints and the first catacombs in the world.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

This Italian foot path winds through the mountains via 52 individual tunnels.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The plague quarantine island home to the alleged "Vampire of Venice."

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

Venice's island of the dead.

A sunken idol welcomes parishioners to Davy Jones' Locker.

The final resting place of the poets Shelley and Keats.

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

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

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