In the San Donato chapel, a real masterpiece rests among the fifteenth-century frescoes in this ancient chapel: the Mausoleum of Bernabò Visconti. This mournful monument is one of the most important sculptures of the late Italian Middle Ages. It's clear that this man joked around very little: he was a tyrannical ruler of Milan, and here you see him in his armor decorated with the coat of arms with a snake, riding a rugged battle-horse.