In 1390, Parasone Grasso, head of the Opera del Duomo (1384-90), engages the Florentine artist Spinello Aretino for six wall paintings dedicated to the Sardinian martyrs Ephesus and Potitus, whose relics were transferred to Pisa in the late eleventh century. Spinello’s frescoes close the gap between the Ranieri and the Job cycles in the south gallery.