Guernica is a town of great importance to the Basques.  It was here under an old oak tree that the leaders of the Basque community met to discuss important matters.  More recently, the town became a focus of Basque hatred for the Franco regime when it was bombed by the Nazi's on the 26th of April 1937 with the full consent of the Spanish government.  The bombing raids flattened the town killing hundreds of people.  It has since been rebuilt.  It is now a rather uninspiring town but still held in reverence by the population.  The spot where the oak tree grew (a 300 year old oak tree still grows there) is protected by a railed off monument and is a place of pilgrimage by Basques from all over the region.  Picasso's famous painting of the bombing outrage "Guernica" is on display in Madrid's Centro de Arte Reina Sofía where it was returned from a New York art gallery in 1981 when Spain returned to democracy.  This was the wish of Picasso.