 After the war the Polish Government retrieved many of the works seized by the Germans.Still more than 1,000 artifacts are missing, including "The Fight Between Carnival and Lent" (which Polish authorities allege was stolen in 1939 by German invaders, reportedly taken away and sold in Vienna, and currently resides in the Kunsthistorisches Museum there) by Pieter Bruegel the Elder (donated to the Museum in 1937 by Stanisław Ursyn-Rusiecki) and priceless others.The Main Building features the newly renovated upper Gallery of the Twentieth Century Polish Art, one of the largest galleries of painting and sculpture from the late 19th century on in Poland, with most celebrated artwork by Jacek Malczewski, Leon Wyczółkowski, Włodzimierz Tetmajer; an extensive collection of works by Stanisław Wyspiański; and also, works by artists of the interwar and postwar periods