Not far from the altar, along the outer flank of the left aisle of the cathedral, is a room in which architecture, sculpture and painting meld in an absolutely unified whole. This space is known as the Piccolomini Library. Here, according to the intentions of Cardinal Francesco Piccolomini, was to be housed the invaluable family collection of books and manuscripts, assembled mainly by his uncle Pius II, the great humanist and himself the author of literary works. In reality the Library never held these volumes but became a magnificent reception room; therefore it was never used for services of worship but wholly devoted to the glorification of the figure of Pius II.
Work began in 1492, when some rooms in the old sacristy were united into one large space covered by a pavilion groin vault; the lower part of the walls was lined with wooden benches carved between 1495 and 1496 by Antonio Barili (later modified and partially destroyed in the eighteenth century). In the center of the room was placed the beautiful marble sculpture group of the Three Graces, an ancient Roman copy of a Greek original, bearing witness to the humanist interests of the Piccolomini family. Then in 1497 the Sienese artist Lorenzo di Mariano, known as Marrina, created the elaborate marble entrance façade separating the library from the left aisle of the church.
But it is the painted decoration, commissioned in 1502 to Pinturicchio, an Umbrian artist at that moment at the height of his fame, that lends this space the magnificence that has enthralled visitors for centuries. As was the custom, the first paintings to be done were the frescoes on the ceiling, in which a major role was played by the numerous assistants the artist called to help him in this undertaking. On the vast surface of the ceiling, along with panels featuring the Virtues and pagan myths, a boundless repertory of ‘grotesque’ decorations unfurls, which at that time represented the very latest in fashionable taste; made up of heterogeneous elements like fantastic creatures, hybrid beings, putti, masks, and vegetable motifs arranged in interweaving patterns, they were inspired by the paintings in the remains of Nero’s Domus Aurea, or Golden House, discovered just a few years earlier and immediately copied and modified by artists who went to Rome to study them in person.
Soon after the ceiling frescoes were finished, in 1503, Francesco Piccolomini died after less than a month of papacy. This caused work to be interrupted; it was resumed in 1505 with the fresco at the top of the façade visible from the cathedral aisle, showing Pius III being crowned pope, commissioned by Andrea di Nanni Piccolomini to honor the memory of his brother who had died two years earlier. Immediately afterwards, keeping his commitment to the wishes of the deceased Francesco Piccolomini, Pinturicchio finally began painting the walls of the room, presenting a veritable “painted biography” of Pius II, divided into ten episodes.
The walls provide a natural framework for the pictures, consisting of ten arches separated by pilaster strips covered with grotesques to imitate a loggia. Each arch thus represents a sort of “window” opening onto a scene, whose subject is indicated in the inscription below it. The ten masterfully painted episodes have always exercised a great visual impact on visitors, first of all because of its brilliant colors which have not faded over five centuries and its extraordinary wealth of detail; secondly, the compositions, even though crowded with figures, are carefully studied to spotlight the protagonist, Pius II, making him immediately identifiable in each of the scenes; and finally, the backgrounds to the episodes alternate green landscapes with views of interiors in a pleasing and never monotonous sequence.
The stories should be read starting from the back right corner, opposite the entrance wall, and proceeding clockwise along the long side of the room in chronological order. The ten episodes illustrate: Enea Silvio Piccolomini Leaving for the Council of Basel; Enea Silvio as Ambassador at the Scottish Court; Enea Silvio Crowned Court Poet by Emperor Frederick III; Enea Silvio Being Reconciled with the Legitimate Pope Eugene IV and Receiving Clerical Orders up to Bishop; Enea Silvio, Bishop of Siena, Welcoming the Imperial Couple Frederick III and Eleonora of Portugal at Porta Camollia; Enea Silvio Chosen Cardinal by Pope Callistus III; Enea Silvio Crowned Pope Pius II; Pius II Summoning the Christian Princes to Mantua to Organize the Crusade against the Turks; Pius II Canonizing Saint Catherine of Siena; Pius II, Already Ill, Reaches Ancona to Begin the Crusade.
Beneath the frescoes, in special showcases, are displayed some rare and precious choir books. Used by the cathedral canons to recite the Hours of the Divine Office, they are adorned with magnificent miniatures painted by Girolamo da Cremona, Liberale da Verona, and other artists from the second half of the fifteenth century.
The tiles on the floor, made by Ginori, are a nineteenth-century replica of the originals in cobalt blue with a gold crescent, the heraldic emblem of the Piccolomini family.