The Bushes set floral wreaths adrift in reflecting pools that mark the former location of the north and south towers. They uttered no words, and walked hand-in-hand on the floor of the cavernous pit, after a slow procession down the long, flag-lined ramp from the street level four to five stories above.
The Bushes then attended a service of prayer and remembrance at nearby St. Paul's Chapel.
The 240-year-old Episcopal church, across the street from the site, escaped damage and became a center of refuge for weary rescue workers.
They were the first stops of nearly 24 hours of observances at the three sites where terrorists wrought death and destruction and transformed his presidency. Nearly 3,000 Americans were killed in the attacks.
On Monday, the anniversary, he is to breakfast with firefighters and other emergency workers at a firehouse in Manhattan; attend a ceremony at the field in Shanksville, Pennsylvania, where one of the hijacked planes hurtled to the ground; and participate in a wreath-laying ceremony at the Pentagon.
He also plans to speak to Americans in a primetime address Monday night from the Oval Office.
Accompanying the president and first lady at ground zero were New York Gov. George Pataki, New York Mayor Michael Bloomberg, and Rudy Giuliani, who was New York mayor at the time of the attacks.
The anniversary of the Sept. 11, 2001, attacks is noted in different ways by Americans, CBS' Jennifer Miller reports.
"It angers me, it really does, it really does," William Harrison, a visitor to New York, said.
For Arlene Russo, the anniversary is one more day — without her son, who she lost on 9/11.
"It's still as fresh as if it were yesterday, it always will be, it
always will be," Russo said.
Across New York, residents marked the day at other ceremonies large and small. From a service of remembrance at St. Patrick's Cathedral in midtown Manhattan to a chant at a Buddhist temple on Staten Island, New Yorkers observed the somber anniversary with prayer and reflection.
Mr. and Mrs. Bush wore grim expressions as they took their places for the interfaith service at St. Paul's.
Both greeted Arlene Howard, the mother of victim George Howard, a New York Port Authority police officer, with a kiss on the cheek. President Bush keeps Howard's badge as a constant reminder of the attacks. His widow sat beside Bush in the front-row pew.
A printed message from the Rev. James H. Cooper said: "The message to people who visit St. Paul's is simple: Go back to your communities knowing that a place of love stood next door to Ground Zero. Try to make the world a better place."
The president's aides have made it clear this is no time for politics, reports CBS News chief White House correspondent Jim Axelrod, although the administration spent Sunday morning making its case about how it has handled of the war on terror since 9/11.