The altar was originally designed by Carlo Rainaldi. Two Ionic columns in pink French marble (two more are set back behind) support the outer fragments of a broken triangular pediment, over which is a curvaceous Baroque dedicatory tablet in black marble flanked by gilded putti. Over this in turn is a segmental pediment containing a gilded winged putto's head, and the cornice of this second pediment flows over the tablet in a serpentine manner.