In this Aug. 6, 1945 photo, smoke rises around 20,000 feet above Hiroshima, Japan, after the first atomic bomb was dropped. On two days in August 1945, U.S. planes dropped two atomic bombs, one on Hiroshima, one on Nagasaki, the first and only time nuclear weapons have been used. Their destructive power was unprecedented, incinerating buildings and people, and leaving lifelong scars on survivors, not just physical but also psychological, and on the cities themselves. Days later, World War II was over. (AP Photo)