The original 15th-century architecture was largely preserved by Bernini who only added a strong stone cornice and embellished the arches with pairs of white stucco statues portraying female saints. The first two pairs on the left and the right are medieval monastic founders and reformers, the rest are all early Christian saints and martyrs. Their names are written on the spandrels of the arches with gilt letters. The cross-vaults remained undecorated and simply whitewashed. The keystones in the nave and the transept are decorated with coats of arms of Pope Sixtus IV. The Della Rovere papal escutcheons were also placed on the cornice of the intrados in the first and the last arches of the nave. These stone carvings are gilt and painted. The nave is lit by two rows of large segmental arched clerestory windows with a simple Baroque stone molding and bracketed cornice. Before the Berninian rebuilding the clerestory windows were the same mullioned arched openings like those on the facade and the bell tower.