Guernica (Picasso, 1937)

Guernica is the definitive anti-war statement of the 20th century, a monochrome fury that condemns the Nazi bombing that killed an estimated 1,600 civilians. Picasso's 349 x 776 cm oil on canvas, completed in just 35 days, uses a chaotic, fragmented composition more emotionally direct than #8's calculated Pointillism. Exhibited at the 1937 World's Fair, it remained in MoMA's custody until 1981—two years after Franco's death—refusing a return to Spain until democracy was restored. Now drawing 2+ million annual visitors to Madrid's Museo Reina Sofia, its power exceeds #5's annual attendance by 1.5 million. The painting's stark, cubist language has been referenced by over 5,000 anti-war protests worldwide since 2000.