A cloud rises following the explosion of an atomic bomb in Hiroshima, Japan, on Aug. 6, 1945.
President Barack Obama will become the first sitting U.S. president to visit Hiroshima on Friday, May 27.
The scale of what happened there — hundreds of thousands killed, countless others sickened by the fallout, the Japanese surrendering days later finally ending World War II in the Pacific — remains a historical moment of a magnitude almost incomprehensible.
The gutted Hiroshima Prefecture Industrial Promotion Hall remains standing on the day of the explosion. Currently known as the Atomic Bomb Dome, the structure now stands as a memorial to those killed in the bombing.
Surveyors measure residual radiation in October 1945 in the ruins of Shima Hospital, located at the hypocenter of the atomic bombing of Hiroshima, as Japan Film Corporation staff film them in Saiku-machi district.
A 21-year-old soldier, who was exposed to the atomic bombing of Hiroshima on Aug. 6, 1945, and has purple subcutaneous hemorrhage spots on his body, received treatment at the Ujina Branch of the Hiroshima First Army Hospital on Sept. 3, 1945.
Victims of the atomic bombing of Hiroshima are sheltered at an emergency relief station in the Otagawa River embankment in Hiroshima on Aug. 9, 1945.
People walk over Aioi Bridge in October 1945 past the gutted dome that is now the Hiroshima Peace Memorial.
Many Americans believe the atomic attacks were justified and hastened the end of the war. However, Japanese survivors' groups have campaigned for decades to bring leaders from the U.S. and other nuclear powers to see Hiroshima's permanent scars.
The B-29 superfortress Enola Gay lands at its Tinian base after its atomic bombing mission over Hiroshima on Aug. 6, 1945.
People walk past destroyed buildings at Aioi Bridge in Hiroshima in October 1945.
Debris covers the ground of Hiroshima in October 1945.
Survey team members confer in front of the large gate on the approach to Hiroshima Gokoku Shrine in the Moto-machi district of Hiroshima in October 1945.
People walk past the Hiroshima Red Cross Hospital in November 1945.
The gutted dome is surrounded by debris in November 1945.