On August 6, 1945, the nuclear weapon "Little Boy" was dropped on the city of Hiroshima, followed on August 9, 1945 by the detonation of the "Fat Man" nuclear bomb over Nagasaki.
Wikipedia link here.
Estimated worldwide nuclear stockpiles (also from Wikipedia).
Ambu sends this link: White Light, Black Rain: The Destruction of Hiroshima and Nagasaki, a HBO documentary film.
UNFORGETTABLE FIRE: Pictures Drawn by Atomic Bomb Survivors.