The Viscontea Raza Sun" refers to a heraldic symbol of the Visconti family, the radiant sun, or "raza" in Milanese dialect, that features prominently in the Duomo di Milano's central rose window and was designed by Michelino da Besozzo. In this central stained-glass window, the sun symbolizes Jesus Christ, representing the victory of light over darkness, while also honoring Gian Galeazzo Visconti for commissioning the Duomo.