Titian: Crowning with Thorns in the Louvre — third from the left in the same room as the Mona Lisa.
The two most famous works ever displayed in the church of Santa Maria delle Grazie in Milan were taken by Napoleon to France and never returned. (Apparently, the Austrians who governed Milan at the time, never asked them back!) Titian’s Crowning with Thorns now hangs in the Louvre in the same hall as the Mona Lisa, while Saint Paul in Meditation by Gaudenzio Ferrari is in the MusĂ©e des Beaux Artes in Lyon.