On the square where the cathedral now stands, called Piano Sancte Marie (the plain of Saint Mary) in medieval documents, as early as the tenth century there was already a little church, located next to the bishop’s residence and oriented in the opposite direction from the current cathedral, with its façade looking towards where the apse is today. During the twelfth century, this church was encompassed in a larger building, turned ninety degrees with respect to the earlier one (facing the square now called Piazza Jacopo della Quercia), until, in the early decades of the thirteenth century, another transformation was set in motion which resulted in the basilica you see now, with the façade definitively oriented towards the Santa Maria della Scala hospital.

We learn from some payment records that in 1263 the dome had already been finished, covered with plates of lead and topped by a copper gilt ball, commonly called the ‘apple.’ The lantern supporting it is the result of a seventeenth-century renovation. By 1284 the nave and side aisles had been built and construction had begun on the façade under the direction of Giovanni Pisano, who worked on it until 1297, finishing the lower section. After he was sent away from Siena, the project was finished twenty years later by Camaino di Crescentino, who took Giovanni’s place as master builder of the cathedral. In the meantime, . . .