More than 40,000 people gathered in Hiroshima on Thursday to commemorate the 70th anniversary of the dropping of the atomic bomb.
Bells tolled in the city seven decades since the city was completely destroyed.
Japan's prime minister Shinzo Abe and foreign delegates were among the thousands who congregated at the Peace Memorial Park to observe a moment of silence at 8:15 am local time, when the detonation turned the western Japanese city into an inferno.
The now-bustling city's mayor Kazumi Matsui said nuclear weapons were an "absolute evil" as he urged the world to put an end to them forever.
"To coexist we must abolish the absolute evil and ultimate inhumanity that are nuclear weapons. Now is the time to start taking action," he said in his speech.
Representatives of more than 100 countries, including the US ambassador to Japan, Caroline Kennedy, were among those marking the anniversary. They heard messages from survivors and local children and the city's mayor, reports The Guardian.
Seven decades ago, the countdown to the first nuclear attack in history began in the early hours of 6 August 1945, when a US B-29 Superfortress bomber, escorted by two surveillance planes, took off from an airfield on the Pacific island of Tinian.
The Enola Gay, named after the mother of the plane's pilot, Brig Gen Paul Tibbets, was carrying a 16 kiloton atomic bomb, nicknamed Little Boy; its target was Hiroshima, a port and major army base in western Japan, six hours' flying time away.
The bomb exploded 580 metres (2,000ft) above a T-shaped bridge at the junction of the Honkawa and Motoyasu rivers, unleashing a blinding flash followed by a deafening boom.
About 70,000 people died instantly in the blast or from the firestorms that raged moments later. The death toll would rise to about 140,000 by the end of 1945. The explosion, equal to 12,000 to 15,000 tonnes of TNT, destroyed more than two-thirds of Hiroshima's buildings across five sq miles.
Lanterns light up the night in memory of fallen