It's not a mysteriously unknown technique, or of particular historical importance, or the only painting by da Vinci. It become famous mostly because of the theft incident and once you're famous the famousness tends to feed itself because people do things like X-ray it which adds to the mystique. It was owned by some famous people including Napoleon and it's spent a lot of time in art museums being shown to the public, but there's no secret message on the back or alien decoder ring or demascus steel/roman concrete "how'd he do it?!" mystery.
It's not a mysteriously unknown technique, or of particular historical importance, or the only painting by da Vinci. It become famous mostly because of the theft incident and once you're famous the famousness tends to feed itself because people do things like X-ray it which adds to the mystique. It was owned by some famous people including Napoleon and it's spent a lot of time in art museums being shown to the public, but there's no secret message on the back or alien decoder ring or demascus steel/roman concrete "how'd he do it?!" mystery.