Arlington National Cemetery, 420 acres (170 hectares), N Va., across the Potomac River from Washington, D.C.; est. 1864. More than 60,000 American war dead, as well as notables including Presidents William Howard Taft and John F. Kennedy, Gen. John J. Pershing, and Admiral Robert E. Peary are interred here. Burial in Arlington is limited to active, retired, and former members of the armed forces, Medal of Honor recipients, high-ranking federal government officials, and their dependents. There are commemorative monuments, including the Tomb of the Unknowns (see Unknown Soldier, Tomb of the). The cemetery is part of "Arlington," the former estate of the Custis and Lee families, and includes Arlington House, now part of Arlington House, The Robert E. Lee Memorial.