The Domitilla’s catacombs are part of a vast funereal complex, a necropolis that holds monuments from the 1st Century AD. Santa Petronilla and the martyrs Nereo and Achilleo are interned here. There are remains of the martyrs in the underground basilica and the entrance bears an inscription to their honour dictated by Pope Damaso. In one of the many cubicles is a painting of Matron Veneranda entering paradise with the martyr Petronilla. This is the first document that refers to Petronilla as a martyr and dates from the first half of the 4th Century.