The floor we see today is the product of a programme that got under way in the 14thcentury but was only completed in the 19th century. The preparatory cartoons for the fifty-six inlay panels were supplied by leading artists, all of them Sienese save for the Umbrian painter Bernardino di Betto known as Pinturicchio, who designed the inlay depicting the Mount of Wisdom in 1505. The technique used to transpose the various artists' ideas onto the floor is known as graffito and mosaic marble inlay.
It is no exaggeration to say that the greatest sculptors of every age have worked for Siena Cathedral. Their number includes Nicola Pisano who carved the pulpit between 1265 and 1268, his son Giovanni who carved the sculptures mentioned above for the façade, Donatello whose surviving work is a statue of St. John the Baptist in the eponymous chapel, Michelangelo who carved St. Peter, St. Paul, St. Pius and St. Augustine for the Piccolomini altar, and Gian Lorenzo Bernini who carved the statues of St. Mary Magdalen and St. Jerome in the "Cappella del Voto" or Chapel of the Vow.
Though many of the Cathedral's panel paintings, canvases and fresco cycles may now be seen in the Museo dell'Opera or in other museums in Italy and abroad, a large number of them are still in situ. Taking them in chronological order, the first one that we should admire is the Madonna del Voto, or Madonna of the Vow, attributed to Dietisalvi di Speme and still in the eponymous chapel today.
The Piccolomini Library is a unique masterpiece of the greatest art-historical importance by virtue of its cycle of frescoes painted by Pinturicchio and his workshop between 1503 and 1508 depicting scenes from the life of Pope Pius II set off by a dazzling vault decorated in the "grotesque" style. Showcases around the Library walls contain 15th and 16th century graduals and antiphonaries decorated with delicate and extremely refined illuminations not only by Sienese artists but also by Liberale da Verona and Girolamo da Cremona, both of them famous illustrators summoned to work in Siena in the second half of the 15th century whose style was to have a major impact on local Sienese painting.
Pinturicchio, Meeting between Frederick III and Eleonora of Aragona
The chancel area hosts four large frescoes by Ventura Salimbeni (1610), who was one of the leading lights in Sienese painting at the turn of the 16th century along with his step-brother Francesco Vanni and with Alessandro Casolani. The frescoes depict the Fall of Manna and Esther and Ahasuerus with Sienese Saints on either side.
Last but not least, the Cathedral's altarpieces are of considerable interest. Little known outside art historical circles, they deserve to attract greater attention inasmuch as they are truly representative of 17th century painting in the broader rather than the strictly local sense, including work by such masters as Carlo Maratta and Mattia Preti.
Carlo Maratti, The Visitation