Guernica (Picasso, 1937)

Pablo Picasso created Guernica in response to the Nazi bombing of the Basque town of Guernica on 26 April 1937, in which 150-1,600 civilians were killed. The 349 x 776 cm monochrome oil painting was exhibited at the 1937 World's Fair in Paris and has become the defining anti-war artwork of the 20th century. Picasso refused to allow the painting to return to Spain until democracy was restored; it remained in MoMA's custody until 1981, two years after Franco's death. It now draws 2+ million visitors annually to the Museo Reina Sofia in Madrid.