On July 16, 1945, the United States successfully detonated the first atomic bomb. But it wasn't until August that the U.S. used the bombs in warfare, dropping them on the Japanese cities of Hiroshima and Nagasaki during World War II.
The so-called "Trinity" nuclear test on July 16 took place in Los Alamos, New Mexico, following years of development. It was the culmination of the Manhattan Project, led by Gen. Leslie Groves and physicist J. Robert Oppenheimer, which produced the atomic bomb.
Seventy years later, we look back at the bomb's development:
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