One of the most famous paintings in the world is at the center of this fourth episode: the Mona Lisa. Who really was the Mona Lisa? Alberto Angela, from the places where Leonardo lived and painted his masterpieces, takes us on a journey through the history of art and, in front of the painting in the Louvre, makes us understand why it is the most famous painting in the world, the most reproduced, and what is so unique and special about this woman who has enchanted courts around the world for 6 centuries.