President Barack Obama is observing the anniversary of the 9/11 terror attacks by visiting all three sites where hijacked planes hit 10 years ago.

The president will finish the day at Washington's Kennedy Center and is expected to call for a spirit of unity and honor the victims of the attacks and the troops who have served in the years since.

Obama was starting the day Sunday in New York City, where he was
expected to give a short reading at the commemoration at ground
zero.

From there he was traveling to Shanksville, Pa., and finally to the Pentagon, before heading to the Kennedy Center event.

The president visited Arlington National Cemetery Saturday to honor troops, and worked at a soup kitchen as part of a day of service.

(Copyright 2011 by The Associated Press. All Rights Reserved.)