Testimony of War
Picasso was inspired to create the work after reading reports of the atrocity carried out by German bombers supporting the Right-wing forces of Gen Francisco Franco.
The attack on April 26, 1937, levelled the historic town during a busy market day causing an estimated 1,650 deaths.
The painting also symbolises the struggle for democracy in Spain. Picasso arranged for the Museum of Modern Art in New York to keep the work for as long as Franco was in power.
The black and white canvas, which is 11ft tall and 26ft wide, was finally moved to Spain in 1981, six years after the death of the dictator, and has remained in Madrid moving to its current location at the Reina Sofia in 1992.
Officials in the Basque country have long argued that the piece which depicts the destruction of the Basque village of Guernica during the Spanish Civil War should be displayed in the region.