UNDATED (CNN) -- Flags are flying at half staff today marking the 11th anniversary of the day hijacked planes hit the World Trade Center, the Pentagon, and a field in Pennsylvania. The unforgettable date is now associated with unforgettable traditions observing the loss.

At Ground Zero, at the Pentagon, in a Pennsylvania field, this was the 11th year people gathered for an anniversary they said doesn't quite feel like history. Sen. Mitch McConnell said in a speech, "Most of us still remember 9/11 like it was yesterday." Sen. Harry Reid said, "A crystal clear morning much like today...." President Barack Obama says, "It was a day like this one--a clear blue sky, but a sky that would soon be filled with clouds of smoke and prayers of a nation shaken to its core."

By now, this date has traditions such as reading the names of 2,753 people who lost their lives in New York, honoring all the victims with moments of silence, gathering at sites that have become sacred ground. Vice President Joe Biden says, "It's a bittersweet moment for the entire nation, all of the country--particularly for those family members gathered here today."

On Capitol Hill, members of congress gathered to remember what was lost and what was saved during the attacks. Speaker of the House Rep. John Boehner says, "The professionals who did their duty, who ran in so others could run out. The patriots who banded together in the sky over Shanksville to save this Capitol and these steps."

Lawmakers sang God Bless America just as they did the day terrorists struck. Partisan politics were set aside at least for the day.

Election year campaigning will be more muted today as the candidates observe 9/11. Mitt Romney marked the anniversary with an impromptu stop in Chicago, meeting firefighters and first responders on a tarmac; President Obama visited wounded troops at Walter Reed National Medical Center.

We have a photo gallery of people in New York City honoring the 11th anniversary of the Sept. 11 attacks.

You can find out more about the anniversary of the September 11 terrorist attacks. There you can find pictures from that day, featured coverage, and hear the stories of people who were there that day and hear their experience and see the front pages of all of the newspapers across the country from September 11 and 12.