At 8:15 a.m. on August 6, 1945, a squadron of B-29 aircraft flew over Hiroshima and the Enola Gay released “Little Boy,” the world’s first atomic bomb. Energy equivalent to 16 kilotons of TNT detonated 1,900 feet above the city, resulting in 4.4 miles of destruction and fire. 30% of the population were instantly killed. The A-Bomb Dome is the ruins of the Hiroshima Prefectural Commercial Exhibition Hall which opened in 1915. The hollow shell was preserved in remembrance of the horror. This UNESCO World Heritage Site is across the river from the Hiroshima Peace Memorial Park.