The president closed his eyes and clasped his hands at the outdoor memorial where the twin towers of the World Trade Center once dominated the Manhattan skyline. He shook hands with 9/11 family members and others dressed in black at the site where the skyscrapers were brought down by planes commandeered by bin Laden's followers. Nearly 3,000 people were killed.
The president met privately at the memorial site with about 60 family members from various 9/11 organizations. He also visited the firefighters and police officers whose response to the terror attacks of Sept. 11, 2001, turned them into heroes and symbols of national resolve, but also cost them heavy casualties on that horrific day.
"This is a symbolic site of the extraordinary sacrifice that was made on that terrible day," the president said at Engine 54, Ladder 4, Battalion 9. The firehouse in New York's theater district lost 15 firefighters on 9/11, more than any other firehouse.
Months before the 10th anniversary of Sept. 11, and days after bin Laden was killed in Pakistan by U.S. commandos, Obama's visit was a day of sober remembrance, thanks given to firefighters, police and U.S. troops, and reminders of the challenges ahead and the president's call for addressing them with unity.
It wasn't a moment for celebrating the military operation that killed bin Laden; that may come Friday, when the president visits Fort Campbell, Ky., home to the Army unit involved in transporting Navy SEALS in and out of bin Laden's compound. White House officials said Obama intended to privately thank participants in the raid.
On Thursday, at the First Precinct police station in lower Manhattan, the first on the scene on Sept. 11, Obama alluded to bin Laden's killing and said of those who died in the Sept. 11 attacks, `'We keep them in our hearts. We haven't forgotten."
Obama said he hoped the results of the raid on bin Laden's compound showed that "we did what we said we were going to do, and that Americans, even in the midst of tragedy, will come together, across the years, across politics, across party, across administrations, to make sure that justice is done."
Obama never mentioned bin Laden by name in his brief remarks to firefighters and police.
Enthusiastic, emotional New Yorkers waited on streets to see the president, but there were few displays like the more raucous exuberance of a few days earlier. There were happy faces, shouts of "USA! USA!" and flags waved in the crowd, but there also was heavy security and most people were cordoned off blocks from where the president could be seen.
At ground zero, the mood was somber, even sad, as the president stood where the towers had been, seeing the faces of the children who lost parents and adults who lost spouses. As Obama bowed his head, a jetliner screamed by far overhead on a blue-sky day.
Former New York Mayor Rudy Giuliani, who led the city in dark days after the attacks, joined Obama during the day.
At the Pentagon, meanwhile, Vice President Joe Biden led a similar wreath-laying ceremony at the site where another hijacked plane crashed into the nation's military headquarters. Among those present was Donald Rumsfeld, who was George W. Bush's defense secretary at the time of the attacks.
Obama invited Bush to join him Thursday in New York, but the former president declined.
Obama's visit came as new details emerged of the daring raid on bin Laden's Pakistan compound. A senior defense official said Thursday that only one of the five people killed in the raid was armed and fired a shot - an account that differs from original administration portrayals of an intense firefight. The White House also now says bin Laden was unarmed when he was shot, after officials initially said the terrorist was holding a gun or even firing.
Such details perhaps mattered little to New Yorkers who suffered most grievously in the attacks and are now deeply gratified to see bin Laden's demise.
Ahead of Obama's arrival, Deanne McDonald stood at the northeast corner of the World Trade Center site waving an American flag in each hand and shouting "Obama got Osama! Obama got Osama!"
"God bless the Navy SEALS," said McDonald, 38, from Brooklyn. She took work off on Thursday to wait for the president, saying she was prouder than ever to be an American.
Obama's New York visit was intended to have a measured tone - not a bookend to Bush's visit after the attacks when Bush took a bullhorn and called out his defiance to the terrorists. Obama spokesman Jay Carney told reporters traveling with the president on Air Force One that the trip was intended in part "to perhaps help New Yorkers and Americans everywhere to achieve a sense of closure with the death of Osama bin Laden."
The bustling construction site that Obama visited bears little resemblance to the pit that remained after the rubble of the towers was removed. The emerging skyscraper informally known as Freedom Tower is more than 60 stories high now. Mammoth fountains and reflecting pools mark the footprints of the fallen twin towers.
Jim Riches, whose firefighter son was among the nearly 3,000 people killed at the World Trade Center, planned to meet with the president on Thursday.
"I just want to thank him, hug him and thank him and shake his hand," Riches said. "Father to father. Thank you for doing this for me."
Obama arrived in New York City Thursday after rejecting calls to release photos of a slain bin Laden so the world could see some proof of death. The president said he would not risk giving propaganda to extremists or gloat by publicizing grotesque photos of a terrorist leader shot in the head.
To those who keep on doubting, Obama said, "You will not see bin Laden walking on this earth again."
The president sought to handle the moment without being seen as overly celebrating bin Laden's death or aiming to boost his own standing.
Al-Qaida terrorists hijacked jets and flew two of them into the World Trade Center's towers. Both buildings collapsed, trapping thousands inside and also claiming the lives of firefighters and others who had rushed to help. A third plane slammed into the Pentagon. Officials have speculated that a fourth plane had been heading for the U.S. Capitol or perhaps even the White House when it crashed after passengers fought back in Pennsylvania.
A few days later, Bush stood amid the rubble and spoke through a bullhorn. When one worker yelled, "I can't hear you," the president responded: "I can hear you! The rest of the world hears you! And the people - and the people who knocked these buildings down will hear all of us soon!"
All these years later, Obama said this was no time for gloating.
Heightened security put in place in response to the killing of bin Laden remained for Obama's visit. Police officials said there were no specific threats against the city but also said they assumed bin Laden's "disciples" might try to avenge his death with a terror attack.
Associated Press writers Verena Dobnik, Colleen Long, Kiley Armstrong, Karen Matthews, David B. Caruso and videojournalist Bonny Ghosh in New York and AP writers Sam Hananel and Pauline Jelinek in Washington contributed to this report.