The brick façade was left incomplete, in the sense that it was never fully faced in marble or stone.
In the interior Giuliano appears to have been influenced by Brunelleschi's design of San Lorenzo, Florence, particularly in the use of alternating columns and pillars, especially noticeable in the arcades separating the central nave from the two side-aisles.
The interior houses numerous works of art, particularly Renaissance sculpture.
Of especial note are: the Chapel of the Blessed Virgin of Graces, built as a diocesan sanctuary, which contains a fresco of 1412, depicting the Blessed Virgin Mary breaking arrows, symbolising the dangers against which she offers protection; the tomb of Saint Terence, made in 1462 by an unnamed Tuscan master; the tomb of Saint Savinus (third quarter of the 15th century), possibly sculpted in Florence by Benedetto da Maiano (brother of the architect); and the tomb of Saint Emilianus from the second half of the 15th century, of which some of the marble reliefs are now in the Musée Jacquemart-André in Paris.
The cathedral also contains a crucifix sculpted by an unknown Northern European wood sculptor (15th century) and, by Innocenzo da Imola, the Bonaccorsi Altarpiece, a 16th-century table still with its original gold and carved cornice and a painting of the Blessed Virgin Mary with the Infant Jesus and Saints John the Baptist, Peter and Paul, Joachim and Ann (oil on canvas, 1526).