When Milan was invaded by the French in 1499 and the Sforza family fled, da Vinci escaped as well, possibly first to Venice and then to Florence. There, he painted a series of portraits that included “La Gioconda,” a 21-by-31-inch work that’s best known today as “Mona Lisa.” Painted between approximately 1503 and 1506, the woman depicted—especially because of her mysterious slight smile—has been the subject of speculation for centuries. In the past she was often thought to be Mona Lisa Gherardini, a courtesan, but current scholarship indicates that she was Lisa del Giocondo, wife of Florentine merchant Francisco del Giocondo. Today, the portrait—the only da Vinci portrait from this period that survives—is housed at the Louvre Museum in Paris, France, where it attracts millions of visitors each year.