A visit to the Cathedral of Siena wouldn't be complete without a stop at the Museo dell'Opera Metropolitana, right next to the cathedral. The gallery collects works from the Duomo, in particular the vast majority of the production of Duccio di Buoninsegna, including the absolute masterpiece Maestą which once adorned the main altar of the cathedral, and the stained-glass window dedicated to the Virgin, originally featured in the apsis.