The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

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

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

A network of underground water channels that dates back to the Middle Ages.

An ancient quarry rediscovered by a dog and claimed by biblical kings, a German cult, and the Freemasons.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.