Leonardo da Vinci painted the Mona Lisa between 1503-1506, making her one of the most famous portraits ever created. Da Vinci was a master of sfumato technique, which uses extremely thin and blended brush strokes to create the illusion of depth. This technique gives Mona Lisa her mysterious smile and makes analyzing her brush strokes very difficult. Hundreds of years later, her enigmatic expression and Da Vinci's artistic genius still fascinate millions of visitors to the Louvre each year who try to unravel the mysteries of her smile and identity.