Year by year, Duccio's painting reaches even higher levels of softness and increased naturalness, while some figurative stereotypes pertaining to byzantine tradition fade away. The red cap the Virgin was always represented with, for instance, especially in the oriental tradition, is now abolished: the veil and the cloak can be more adherent to the figure, giving it a newer elegance, increased by the calligraphic swirls of the hems slipping on shoulders and chest.


In 1308 documents begin to report the greatest masterpiece of the craftsman, the huge 'Maestà' for the high altar of the Sienese Duomo, bearing on the backside 25 tales of the 'Passion of Christ', completed by other episodes of 'Life of Christ and Mary' in the predella and in the crowning.
On June 9th, 1311, the huge altarpiece was triumphally transported from the artist's bottega to the cathedral, with a long procession followed by the music of the trumpets.
After this we have no more documentary news related to Duccio's painting activity; it is possible however to date back to around 1314 the fresco depicting the "Consegna del castello di Giuncarico", painted on a wall of the Sala del Mappamondo in the Palazzo Pubblico in Siena, right under Simone Martini's Guidoriccio da Fogliano.
This is the last known work of the craftsman, who died around 1318-1319, year during which his sons decided to refuse his inheritance, probably laden by debts.