More than 100 cyclists gathered in Washington on Saturday, the 69th anniversary of the U.S. atomic bombing of Nagasaki, to call for the global abolition of nuclear weapons.

At the event, organized by anti-nuclear advocate group Global Zero, participants rode bikes over an 11-kilometer course encompassing the White House and Congress building, as well as other major landmarks in the U.S. capital.

The bike route was chosen, based on a hypothetical calculation, the area that would be devastated if an atomic bomb the size of those used on Hiroshima and Nagasaki was dropped on Washington.

"The ride today is symbolic," said Erin Finucane, global campaign director for Global Zero.

Organizers wanted to "challenge" participants to think about what a nuclear catastrophe would look like in their own community, she added.

Prior to the start of the ride, former U.S. Assistant Secretary of Defense Lawrence Korb addressed the crowd and stressed the importance of putting denuclearization "back on the agenda" of U.S. President Barack Obama, who has pledged to seek a world without nuclear weapons.

"He's got two years left, we've got to make him do it," Korb said, pointing out the danger of keeping nuclear stockpiles. "This would be a great legacy for him."

The event was the first of its kind to be held in Washington. Similar events took place simultaneously in London, Berlin, Islamabad, Lahore and New Delhi.

"Our message to Obama is clear — zero is the only option," Finucane said.

Global Zero wants to see the elimination of all nuclear weapons by 2030.