Cardinal Francesco Todeschini Piccolomini, archbishop of Siena (later Pope Pius III), commissioned the building and decoration of this hall off the north aisle of the duomo in 1492 to house the books of his uncle, Enea Silvio Piccolomini (Pope Pius II). Come here not to see the books (only a series of huge choral tomes remains on display), but to enjoy the vividly coloured narrative frescoes (1503–08) by Pinturicchio (Bernardino di Betto), which depict events in the life of Pius II.

　　The magnificent 10-fresco cycle starts with a depiction of the future pope's early days as a secretary to an Italian bishop on a mission to Basel, moves through his ordinations as bishop and pope, and ends with his death in Ancona while trying to mount a crusade against the Turks. In the centre of the hall is a group of statues known as the Tre Grazie (Three Graces), a 3rd-century Roman copy of an earlier Hellenistic work.