How many laboratory tests verified da Vinci 's " Lady with an Ermine " ?
Polish museums exhibit remarkable art collections - masterpieces including Leonardo da Vinci 's Lady with an Ermine at the Czartoryski Museum in Kraków ; the Veit Stoss High Altar in St. Mary 's Basilica , Kraków ; and the Last Judgement by Hans Memling ( The National Museum in Gdańsk ) .