As Memorial Day approaches, every service member buried at Arlington National Cemetery is honored by having a flag placed on their grave. The ceremony, known as "Flags In," takes place every year. Soldiers from the 3rd U.S. Infantry Regiment, known as The Old Guard, have put American flags at each grave for more than 60 years. Today, there are more than 228,000 headstones. It takes the soldiers four hours to complete the task.