FILE - -In this file photo taken April 12, 2011 at the Royal Castle in Warsaw, Poland, art conservators Janusz Czop, left, and Janusz Walek, right, present to journalists Leonardo da Vinci painting "Lady with an Ermine," Poland's most valuable picture. UNESCO Director-General Irina Bokova and Poland's Culture Minister Piotr Glinski appreciated the painting Sunday, July 2, 2017, at the National Museum in the southern city of Krakow, before opening the 41st annual session of UNESCO World Heritage Committee that runs through July 12. (AP Photo/Alik Keplicz, File)