The 17C basilica, depicted by a rich baroque interior, stands on the burial place of Saint Gaudioso, a bishop martyr from Bethany, who sought sanctuary in Naples in 439. The catacombs house the saint's tomb, of which only the funerary inscription remains, as well as Paleo-Christian mosaics and frescoes. The 16C Galleria dei Nobili dates from the time when the catacombs were used by the Dominican brothers and the local aristocracy.