Three sketches found under Leonardo da Vinci painting . After the art experts began studying the circa 1500 painting , an oil on wood , a conservator from the Paintings Department discovered two barely visible drawings on the back of it -- a horse 's head and a partial skull . The first sketch is a drawing of the Mona Lisa by Leonardo Da Vinci. Drawings are a horse 's head , a partial skull and infant Jesus with lamb .
Three sketches found under Leonardo da Vinci painting . The first sketch is a drawing of the Mona Lisa by Leonardo Da Vinci. Drawings are a horse 's head , a partial skull and infant Jesus with lamb .