Dug between the 2nd and 5th centuries, this vast network of burial chambers was known as the Queen of Catacombs. As an early Christian burial site, numerous martyrs and popes are buried in the 40,000 tombs and chambers lining the 13km of tunnels.
Tours of the catacombs (English and Italian) visit a remarkable 3rd-century Greek chapel and a rough fresco of the Virgin Mary and Christ child, thought to be the oldest existing image of the Madonna.