The altar wall has four windows, two square ones over two rectangular ones, and these windows have splayed frames facing the altar in order to maximize the natural light falling onto it. Below the entablature is a broken triangular pediment into which a dedicatory epigraph on an oval tablet is inserted. This pediment also has a pair of angels reclining on it. The lunette above the entablature has a large trapezoidal window, flanked by frescoes of two prophets accompanied by angels and putti. These are by Cesare Nebbia. A third pair of stucco angels is over the window, supporting a second dedicatory tablet.