Live Stream interview by Martin Willis with a leading world Leonardo da Vinci expert, Martin Kemp on Leonardo’s Salvator Mundi, the most expensive painting ever sold at auction ($450 million). This unknown work was purchased by a New York art collector Robert Simon for $10,000 through an auction house somewhere in Louisiana in 2005. The mystery buyer at auction was prince, Bader bin Abdullah bin Mohammed bin Farhan al-Saud.