The altar is the center of the house of worship, the visible sign of Christ, the cornerstone on which God builds the Christian community. The original altar of the cathedral, on which the great Maestà by Duccio stood from 1311, was replaced in 1532 by the one still there today, designed by Baldassare Peruzzi. In any case, Duccio’s altarpiece had already been removed a few years earlier, in . . .