"Guernica" by Pablo Picasso.
Guernica was created in response to the bombing of Guernica, Basque Country, by German and Italian warplanes at the behest of the Spanish Nationalist forces, on 26 April 1937, during the Spanish Civil War. The Spanish Republican government commissioned Picasso to create a large mural for the Spanish display at the Paris International Exposition at the 1937 World's Fair in Paris.
Guernica shows the tragedies of war and the suffering it inflicts upon individuals, particularly innocent civilians. This work has gained a monumental status, becoming a perpetual reminder of the tragedies of war, an anti-war symbol, and an embodiment of peace. On completion Guernica was displayed around the world in a brief tour, becoming famous and widely acclaimed. This tour helped bring the Spanish Civil War to the world's attention.
While living in Nazi-occupied Paris during World War II, Picasso suffered harassment from the Gestapo. One officer allegedly asked him, upon seeing a photo of Guernica in his apartment, "Did you do that?" Picasso responded, "No, you did." (read more)