In the most emotional part of the ceremony, the names of the 168 victims were read aloud, grouped according to the floor they were on during the bombing. With their voices sometimes quavering, sons, daughters, brothers, sisters, parents, and spouses of the victims took their turn at the microphone. The victims came from different parts of the federal government -- from the U.S. Secret Service to the Social Security Administration to the America's Kids day care center, where over a dozen young children lost their lives.
One of those children, Baylee Almon, would have turned 16-years-old this week. In the years since the attack, her mother has turned her grief over the loss into action, crusading to make federal buildings safer with shatter-resistant glass.
"Her death, to me, wasn't for nothing," said Aren Almon-Kok. "It was so maybe others could make a difference. So other people can go home to their families at night."
Many of the children who survived the explosion are now in college and high school. Chris Nguyen was in the day care center, and doctors weren't sure the 5-year-old would live. Today, he is a sophomore at Oklahoma University.
"After all these years of researching it and figuring out what happened, kind of piecing everything together myself, it stuns me that the survivors made it through," Nguyen said.
The ceremony ended with bagpipe music, and state leaders promised to remember the lessons of the bombing and the way it brought a community together.
"The Oklahoma Standard is not a past event," said Gov. Brad Henry. "It is part of the character and fabric of the people of this city and state."
ABC's Ryan Owens contributed to this report from Oklahoma City.