Dug between the 2nd and 5th centuries, this network of creepy tunnels was known as the Queen of Catacombs. It was an important early Christian burial site and numerous martyrs and popes were buried in the tombs and chambers that line the 13km of tunnels.

Visits take in a decorated Greek chapel and a scratchy fresco of the Virgin Mary with the baby Jesus on her lap. Dating to around AD 230, this is thought to be the oldest existing image of the Madonna.