"In the mid-1460s Pope Pius II commissioned four of Siena's leading painters to execute altarpieces for his newly completed cathedral in Pienza. These were the two slightly older painters Sano di Pietro and Giovanni di Paolo, the tried and tested Vecchietta, and a younger painter, Matteo di Giovanni. The cathedral was built by the Florentine architect Bernardo Rossellino according to the patron's taste for both Italian renaissance architecture and the tall, luminous interiors of north European churches, it was furnished entirely according to his preferences and wishes.Each of the four painters executed an altarpiece whose form and subject matter appears to have been closely controlled by their humanist patron. Vecchietta's takes the distinctive form of a kind of unified triptych, depicting the Virgin of the Assumption in the centre and pairs of saints on either side. These are Agatha, Pius, Calixtus and Catherine of Siena. Destined to be placed over the altar in the chapel to the left of the central chapel (when facing towards it), its subject honoured the dedication of the cathedral to the Virgin of the Assumption; the identities of the patron, Pius II, and his own patron and papal predecessor, Pope Calixtus III; and the Sienese saint whom Pius had canonised in 1461.While recalling the original design and gilded magnificence of the patronal altarpieces for Siena cathedral, this altarpiece was rendered in a notably contemporary manner, the framework adopting the repertoire of Renaissance architecture - simple, rectangular mouldings and a round (not pointed) arch, surmounted by a triangular pediment. The central image of the Virgin of the Assumption also demonstrates Vecchietta's confident handling of pictorial spaces, both in terms of the angels grouped in a circle below the seated figure of the Virgin and in the lyrical landscape behind the figure of Saint Thomas in the lower foreground. The pairs of saints on either side of this image stand on a pavement embellished with circles, likewise seen in depth. These saints too are portrayed as substantial figures who relate to one another."