The altar is dedicated to St. Pope Dionysius (Denis). Similar to the left transept altar, the altar table and frontal are medieval with ‘cosmatesque’ mosaic inserts, and there is ‘cosmatesque’ work set into the predella as well. In the lower foreground of the altarpiece is the coat-of-arms of Lucrezia Tomacelli-Colonna, indicating that it was she who commissioned the piece