 They stood originally in the center of the nave but were moved to the apse around 1540.Behind the altar are a series of damaged Gothic frescoes dedicated to the life of the Virgin Mary, occupying the three walls completely.They were created around 1370 by the local artist Ugolino di Prete Ilario and a few collaborators such as Pietro di Puccino, Cola Petruccioli and Andrea di Giovanni.