OBAMA BUSH JOIN TOGETHER FOR A FIRST AT 9/11 CEREMONY

President Barack Obama and first lady Michelle Obama former President George W. Bush and former first lady Laura …

It was poignant, solemn, and a first for them both: President Barack Obama and former President George Bush, side-by-side, at site of the former World Trade Center towers.

[Photos: Memorable moments from the Ground Zero memorial ceremony ]

Last spring, just days after Osama bin Laden was killed by U.S. forces, Obama flew to New York City for a few moments at Ground Zero, to honor those who had fallen in the terrorist attacks.

But when he extended an invitation to former President George W. Bush, the invite was declined.

On Sunday, the two stood quietly in front of the bronze parapets that surround the giant reflecting pools, which stand in the exact footprints of the former twin towers.

First Lady Michele Obama stood by the president's side, and Laura Bush stood next to the former president.

On May 5, when he visited the site, Obama noted, "It didn't matter who was in charge, we were going to make sure that the perpetrators of that horrible act -- that they received justice."

At the time, the former president wished to remain out of the spotlight, CNN reported a Bush spokesman saying. But today's ceremony unified the two families, and was marked by the memorable gesture when Michele Obama comforted Laura Bush as she broke down in tears.