Arlington National Cemetery is a military cemetery situated directly across the Potomac River from the Lincoln Memorial in Washington, D.C. It was originally built as a memorial to George Washington and later purchased by Congress in 1883. It is the burial site of former U.S. Presidents John F. Kennedy and William Taft, and serves as the burial site for veterans and military casualties from each of the United States' wars (American Civil War through Afghanistan and Iraq wars).
In regards to black history, there are around 3,800 former slaves buried in the cemetery, whose head stones are easily recognizable because of the inscriptions "citizen" or "civilian". According to an article in the Chicago Tribune, "There is one man in the cemetery who was also born on the property. His name is James Parks and he was a slave there that dug some of the very first graves in Arlington National Cemetery. Parks is buried in section 15." (Source)