What group that keeps vigil day and night over the tomb of unknown?

The group that keeps vigil day and night over the Tomb of the Unknown Soldier is the United States Army's Tomb Guard. These soldiers are part of the 3rd U.S. Infantry Regiment, also known as "The Old Guard," and they perform a ceremonial duty to honor and remember unidentified service members who sacrificed their lives. The Tomb Guard is known for its meticulous precision and dedication, ensuring that the tomb remains a solemn and respectful site for visitors.