People interested in this might also like his self-promoting letter to the Sultan of the Ottoman Empire, a little later in life: http://newswatch.nationalgeogra

People interested in this might also like his self-promoting letter to the Sultan of the Ottoman Empire, a little later in life: http://newswatch.nationalgeographic.com/2013/01/22/leonardos-bridge-part-2-the-bridge-for-the-sultan/ http://newswatch.nationalgeographic.com/2013/01/22/leonardos... Best link I could find at short notice, unfortunately, the letter excerpt is two paragraphs in.