The "Museo Nacional Centro de Arte Reina Sofia" hosts many modern art pieces.
The most famous of the pictures you can see here is the "Gernika", a work by Pablo Picasso. Picasso painted the picture after the Nazi bombing of Gernika during the Spanish Civil war (1936-1939). This huge canvas features many distorted human figures denouncing the fascist attack. When Nazi officials asked Picasso if he was the responsible for the painting, he answered: "No, you are".
Picasso gave the work of art to the New York Museum of Modern Art, on condition that it came back to Spain after democracy was restored.