Claim: Guillaume de Marcillat, who was employed by the popes Julius II and Leo X in the Vatican in 1509, produced windows for the Cathedral of Arezzo, a Roman Catholic cathedral in the city of Arezzo in Tuscany, Italy, and the Basilica of San Francesco by 1519.
Evidence: He was in Rome by 1509, where he was employed by the popes Julius II and Leo X in the Vatican and at Santa Maria del Popolo, where the two windows in the choir are his earliest surviving works. Donato e Pietro) is a Roman Catholic cathedral in the city of Arezzo in Tuscany, Italy. Arezzo Cathedral (Italian: Cattedrale di Arezzo, Duomo di Arezzo, Cattedrale di Ss. By 1519 he was in Arezzo, where he produced windows for the Cathedral of Arezzo and the Basilica of San Francesco.