This year marks the 65th anniversary of one of the most disastrous and tragic events in the history of humankind. Hiroshima Day is observed in many parts of the world with special vigils and peace marches. It is held to commemorate the dropping of the first atomic bomb on the Japanese city of Hiroshima on August 6, 1945. Watch this video of a survivor describing the Hiroshima bombing. Three days later a second bomb fell on the city of Nagasaki. "Peace Day" was declared on the first anniversary of the bombing of Hiroshima by the Japanese to try to ensure that the horrendous, enduring effects of nuclear warfare would never be repeated.