Sassetta, the subtle genius from Siena, revolutionized Italian painting with an altarpiece for the small Tuscan town of Borgo San Sepolcro in 1437–1444. Originally standing some six yards high, double-sided, with a splendid gilt frame over the main altar of the local Franciscan church, it was the Rolls Royce of early Renaissance painting. But its myriad figures and scenes tempted the collectors of the nineteenth and twentieth centuries, and today its disassembled panels can be found in twelve museums throughout Europe and the United States. To produce this landmark volume, experts in art and general history, painting technique and conservation, woodworking, architecture, and liturgy have joined forces across the boundaries of eight different nations. A model of collaboration, it opens new windows onto the creative process of the artist as he confronted a late-medieval church at a crossroad of cultures, the miracle-working body of a holy man, and a community of Franciscan friars breathing the exhilarating air of reform. To confront such challenges, Sassetta raised the most spiritual school of early Italian art, the Sienese, to a higher level of understanding, grace, and splendor.