The impressive brick construction of the nave is visible from the piazza on the right hand side. The first storey has an entablature with dentillate cornice of which has a very deep overhang. Above this, massive pilaster buttresses rise to an equally deep cornice on the roofline, and this cornice follows the tops of the buttresses to give a powerful crenellated impression. The fabric is in brick, with some details in travertine limestone. The façade is entirely faced in travertine. There is a central dome over the crossing of the transept, slightly elliptical, of lead with eight ribs. It sits on an octagonal drum with recessed sides, each with a window, and has a lantern with a ball finial.