While Memorial Day weekend is celebrated as the unofficial start of summer, its beginning was solemn and a time to honor those who paid the ultimate sacrifice in the Civil War as their graves were adorned with flowers. Across the country, Memorial Day will be marked with a National Moment of Remembrance at 3 p.m. on Monday, May 26 as many people visit cemeteries and memorials to honor and mourn those who died while serving in the U.S. military.