The Piccolomini Library, incorporated into the northwest side of Siena Cathedral houses precious illuminated choir books and frescoes painted by Pinturicchio, probably based on designs by Raphael. The frescoes tell the story of the life of Siena's favourite son, cardinal Enea Silvio Piccolomini, who eventually became Pope Pius II. He was the uncle of cardinal Francesco Todeschini Piccolomini. The frescoes depict ten remarkable events from the secular and religious career of Pope Pius II, first as a high prelate, then bishop, a cardinal and ultimately pope[2]. For this scene there are Raphael's preparatory drawings, especially with regard to the ride[3].

Raffaello Sanzio (1483-1520), model for Enea Silvio Piccolomini parte per il concilio di Basilea

Enlightening, even as a means of attribution, is the comparison between the works of Pinturicchio, humiliating the open space of Raffaello’s drawing by over-planning the rugged, walled-city in the background. The clothes of the various protagonists are different and the approaching storm, only just visible in Raphael’s drawing, is dramatic in that of Pinturicchio. It is impossible that the drawing is a copy of the fresco because of the many differences in structure and composition, nor was it drawn by Pinturicchio as some scholars believed, refusing Vasari’s opinion that Raphael had given his friend “ the sketches and cartoons” for the fresco in Siena. At the top may be read the story of the adventurous journey of Cardinal Enea Silvio Piccolomini, the future Pope Pious II, and may be dated about the end of 1503.(4)