The magnificent chapel, commissioned by Cardinal Alessandro Riario in 1585, designed by Giacomo della Porta, was then executed by Martino Longhi and decorated by Cristoforo Roncalli. The cardinal's coat-of-arms can be seen on the balustrade. The large apse has five windows, three over two, and a conch. The latter is coffered in diapers with rosettes, while the single-bay sanctuary has a short barrel vault with octagonal coffering.