Union dead were buried on the grounds of Arlington House in 1864. Shortly thereafter, on June 15 of that year, Quartermaster General of the Army Montgomery C. Meigs petitioned Secretary of War Edwin Stanton to establish a national cemetery on the site. Meigs, although born in Georgia, viewed Confederates as traitors and had a deep-seated vindictiveness toward the South and toward Lee in particular. Meigs assigned his assistant, Edward Clark (later Architect of the Capitol), to lay out the grounds. Clark's design—since extended—follows the topography with the curvilinear roads popularized by the rural cemetery movement. By the end of 1864 more than 7,000 Union dead had been interred, and by the end of the war, more than 16,000. In April 1866, in Mrs. Lee's former rose garden, Meigs had erected the Tomb for the Unknown Dead from the war, which contained the remains of 2,111 soldiers. Nearby he erected a Temple of Fame, a colonnaded gazebo dedicated to the memory of George Washington and eleven Union generals. This was removed in the 1960s during restoration of Arlington House. Meigs's own memorial (and his family's) is 100 yards east of the former rose garden. In 1868, the first Memorial Day, then called Decoration Day, was declared at Arlington Cemetery.
The initial government cemetery encompassed 200 acres immediately surrounding Arlington House; in 1897 it took in 408 acres, and then in 1981 an area of Fort Myer was added, making the total 612 acres. The formal entrance at the Virginia terminus of Memorial Bridge was part of William Kendall's bridge scheme (1923–1932, McKim, Mead and White) and follows the stock classicism of that firm. Immediately behind it is the United States Women's War Memorial (1995–1998, Manfriedo and Weiss), which consists of glass shafts and lights, especially effective at night. Among the notable monuments are Major Pierre Charles L'Enfant's tomb, directly in front of the mansion; the John F. Kennedy grave (1965–1967, John Carl Warnecke); the Confederate Monument (1906–1914, Moses Ezekiel, sculptor; dismantled in 2023), a 30-foot-tall shaft crowned by Vindicatrix; the Canadian Cross (1927, Sir Reginald Blomfield); the General George B. McClellan Arch (c. 1875, Lot Flannery), also 30 feet tall; and the United States Coast Guard Memorial