The main altar was commissioned by Cardinal Neri Corsini and designed by the architect Nicola Salvi. He made it into an elegant and refined synthesis of marble and gilded metal. The top of the altar rests on an urn in porphyry rosso antico, the costly stone of the ancients, that contains the putative relics of Saint Eustace. The altarpiece was painted in 1727 by Francesco Ferdinandi (1679–1740), also named "l'Imperiali". It represents the martyrdom of Saint Eustace and his family who were roasted to death inside a bronze statue of a bull or an ox, in the year AD 118. The gilded wooden baldachin (circa 1746) over the main altar is attributed to Ferdinando Fuga (1699–1781).