The Japanese city of Hiroshima today remembered the 69th anniversary of the U.S atomic bombing on Wednesday. Ten of thousands, including survivors of the destruction gathered in Peace Memorial Park to remember the atrocity.

The crowds, including U.S. Ambassador to Japan, Caroline Kennedy observed a moment of silence at 8:15am, the time in which the bomb destroyed the city in a ball of fire.

Hiroshima Mayor Kazumi Matsui urged world leaders of nuclear nations to visit the city to see the evils of nuclear weapons.

He stated, "President Obama and all leaders of nuclear-armed nations, please respond to that call by visiting the A-bombed cities as soon as possible to see what happened with your own eyes," Matsui said.

"If you do, you will be convinced that nuclear weapons are an absolute evil that must no longer be allowed to exist."

In 1945, the United States used a massive, atomic weapon against Hiroshima, Japan. This atomic bomb, the equivalent of 20,000 tons of TNT, flattened the city, killing tens of thousands of civilians.

While Japan was still trying to comprehend this devastation three days later, the United States struck again on the city of Nagasaki.

There are about 190,000 survivors from the nuclear attack still alive.

The commemoration is ahead of the review of the Nuclear Non-Proliferation Treaty, the main forum for nuclear disarmament.