The left transept was decorated by the Sienese painter Pietro Lorenzetti and his workshop between 1315 and 1330 (attributed by Vasari to Pietro Lorenzetti and also (wrongly) to Giotto and Puccio Capanna) . This cycle of tempera frescoes are his masterworks. They depict six scenes from the "Passion of Christ". The fresco of "Deposition of the Cross" is especially emotional. There were about 330 work-stages needed to complete this cycle. Beneath the monumental "Crucifixion" scene, Pietro Lorenzetti has executed a fresco of the Madonna and Child, accompanied by Saints John the Evangelist and Saint Francis (the so-called "Madonna dei Tramonti"). The fresco is accompanied by a frescoed niche containing the liturgical implements and a fictive bench.