Tens of thousands of visitors are expected to flock to Arlington National Cemetery this week to pay their respects to the servicemen and servicewomen who have fought for our freedom.

Thursday afternoon, in advance of Memorial Day, soldiers from the 3rd U.S. Infantry Regiment started inserting 220,000 American flags in front of every headstone in the cemetery. The regiment is stationed at Joint Base Myer-Henderson Hall in Arlington.

The official Memorial Day observance is scheduled for 11 a.m. Monday. A prelude concert by the United States Army Band will be held in the cemetery's amphitheather at 10:30 a.m.

No tickets are required for the event, but those who wish to attend are advised to arrive between 8 a.m., when the cemetery opens, and 9:30 a.m.

The National Weather Service is predicting high temperatures to top out around 93 degrees on Monday. The cemetery is encouraging guests to bring clear plastic refillable water bottles to stay hydrated.