At sunset, the Ponte Vecchio and the Arno below are bathed in a golden hue that rivals the goldsmiths’ showcases inside. Starting in the 13th century, the covered bridge was filled with butchers and fish markets. But when Duke Ferdinando I got tired of the stench and pollution, he declared in 1593 that only jewelers and gold merchants could sell here … a tradition that’s lasted over 400 years. At night, most of those green shutters close until morning.