President Barack Obama has several planned events on Memorial Day, the holiday that honors men and women who died while serving in the U.S. military.
Obama hosted a breakfast for military and veteran service groups, as well as senior military leaders, at the White House Monday morning.
Later, the president took part in a Memorial Day observation at Arlington National Cemetery where he laid a wreath at the Tomb of the Unknown Soldier.
WATCH: Obama at Arlington National Cemetary
The U.S. observes the holiday on the last Monday of May.
Obama said in his weekly address: "The debt we owe our fallen heroes is one we can never truly repay."
WATCH: National Memorial Day Concert
Sunday night a free Memorial Day concert, headlined by the 1960s group The Beach Boys, was held on the west lawn of the U.S. Capitol.
The event was hosted by actors Gary Sinise and Joe Mantagna, and was broadcast on PBS and the American Forces Network.
The first large-scale observance of what was originally called Decoration Day took place at Arlington Cemetery in 1868, three years after the bloody U.S. Civil War that killed more than 600,000 people.
Now, the three-day weekend is seen as the unofficial start of the summer vacation season. Many Americans have the day off from work and school, and many families have picnics or make trips to the beach, parks or campgrounds.