The church's exterior gives little indication of the treasures that lie inside, such as the large crucifix, painted in 1550, which is suspended in the middle of the central nave. The numerous paintings on display include a lovely St Catherine (1596) by Giuseppe Alvino. However, it is the works by Gaspare Bazzano which are particularly striking, including the grandiose St Mary of the Angels and the frescoes in the chancel.