Saturday, President Obama participated in a somber commemoration at the Pentagon, laying a wreath in memory of those people who lost their lives when a plane crashed into the nation's military headquarters.
Another ceremony took place in Shanksville Pennsylvania Saturday, where Flight 93 crashed after the passengers confronted their hijackers.
There, Michelle Obama was joined by former first lady Laura Bush in remembering the valiant passengers. "We saw the worst of our enemy and the best of our nation."
"I come here today not just as First Lady, on behalf of my husband and a grateful nation. I come as an American, filled with a sense of awe at the heroism of my fellow citizens," Michelle Obama said.
But perhaps the most vivid reminder of the day was at Ground Zero in New York where relatives read the names of those killed when the World Trade Center went down.