Guernica, one of Picasso's most important paintings, and a specifically Spanish work, can be seen in the Museo Nacional Centro de Arte Reina Sofia in Madrid. However, this was not always the case, as
The Oxford History of Western Art explains:
In 1937, Picasso produced the large-scale painting Guernica, a work which has subsequently become one of the most famous anti-war statements made in the history of art. Guernica was originally produced in response to a commission from the Spanish Republican government for a work to be installed in their pavilion at the 1937 Paris International Exhibition. Uncertain, at first, how to approach the commission, Picasso was soon swayed by the events of 26 April 1937. On that day Franco's forces, assisted by the German Condor Legion, bombed the small Basque town of Guernica, killing hundreds of civilians. The atrocity made international headlines and photographs of the destruction were reproduced in many newspapers worldwide.
Picasso's Guernica draws attention both to the possibilities and limitations of using a modernist visual vocabulary, to produce what is, in effect, a large-scale history painting. His schematic handling and tortured, fragmented forms adequately symbolise the tragedy of civilian bombing, whether through the representation of the agonized mother carrying a dead child in the left of the image, or through the noiseless scream of the dying horse which dominates the centre. By producing the whole image in black and white, Picasso also alluded to the newspaper and newsreel coverage of the event in the international arena. Nonetheless, Picasso's complex stylistic handling, composition, and symbolism were unlikely to appeal to a broad audience, making his work inaccessible to many.
Following its exhibition in Paris, Guernica was sent on tour to Britain and the United States to raise money for the Spanish Republican cause. After the final victory of Franco the work remained in the Museum of Modern Art in New York. It was not until 1981, and after the deaths of both Franco and Picasso, that the work would finally return to Spain.