Perhaps the single most famous work of art in the world, this mysterious portrait was painted by Leonardo da Vinci around 1503. The painting was not particularly well-known  until the mid-1800's, though many previous historical figures had called it a prize possession, Louis XIV and Napolean among them. It is among the first portraits to be painted in front of an imaginary background, and the model's lack of eyebrows (it was common for wealthy women to pluck their eyebrows at the time) combine with her implacable smile and da Vinci's masterful chiaroscuro to create an almost haunting effect.