The Mona Lisa is the most celebrated painting in the history of art. It is also one of the most mysterious. Who is hiding behind the famous smile? Why he mourning veil? Why the tormented landscape? Is the title still legitimate? Combining close-ups with X-rays, copies, and analogies, this detailed study of the Mona Lisa allows us to better understand the enigma as it unveils the many facets of this incomparable work of art.