The decoration includes stuccoes by Francesco Ferrari (c. 1725), and a Cosmatesque pavement. The main altarpiece has a "Madonna with Saints Andrew and Gregory" (1734) by Antonio Balestra. The second altar on the left has a "Madonna on a Throne with child and four Saints and Blesseds of the Gabrielli family" (1739) by Pompeo Batoni. At the end of the nave, the altar of S. Gregorio Magno has three fine reliefs from the end of the 15th century by Luigi Capponi. Also interesting is the "Salviati Chapel", designed by Francesco da Volterra and finished by Carlo Maderno in 1600: it includes an ancient fresco which, according to the associated tradition, spoke to St. Gregory, and a marble altar (1469) by Andrea Bregno and pupils. The chapel is used by Rome's Romanian community, which follows the Byzantine rite there. To the left of the church, tightly grouped in the garden, are three oratories commissioned by Cardinal Cesare Baronio at the beginning of the 17th century, as commemorations of Gregory's original monastery. The central oratory has frescoes of the "Flagellation of Saint Andrew" by Domenichino; a "Saint Andrew brought to the temple" and "Saints Peter and Paul" by Reni; a "Virgin with Saints Andrew and Gregory" by Cristoforo Roncalli, "il Pomarancio"; and finally "S. Silvia e S. Gregorio" by Giovanni Lanfranco. The oratory to the viewer's right is dedicated to St. Silvia, St. Gregory's mother: it is probably located over her tomb. This oratory has frescoes of a "Concert of Angels" by Reni and "David and Isaiah" by Sisto Badalocchio. This oratory, with frescoes (1602) by Antonio Viviani, represents the rebuilding by Cardinal Baronius (1602) of the famous "triclinium" where St. Gregory hosted a meal every day for a dozen poor men of Rome. At the massive marble table on antique Roman bases, at odds with Gregory's reputation for asceticism, John the Deacon tells that an angel joined the twelve poor men who gathered at the table to partake of Gregory's beneficence. The marble table-supports take the form of addorsed, winged lions whose heads sprout goats' horns.