Arlington National Cemetery is a United States military cemetery in Arlington County, Virginia, across the Potomac River from Washington, D.C., in whose 624 acres (253 ha) the dead of the nation's conflicts have been buried, beginning with the Civil War, as well as reinterred dead from earlier wars. The United States Department of the Army, a component of the United States Department of Defense (DoD), controls the cemetery. The national cemetery was established during the Civil War on the grounds of Arlington House, which had been the estate of Confederate general Robert E. Lee's wife Mary Anna (Custis) Lee (a great-granddaughter of Martha Washington). The Cemetery, along with Arlington House, the Robert E. Lee Memorial, and the U.S. Marine Corps War Memorial, form the Arlington National Cemetery Historic District, listed on the National Register of Historic Places in April 2014. The cemetery conducts between 27 and 30 funeral services every weekday, and between 6 and 8 services on Saturday. The cemetery has been expanding by roughly 30 acres (12 ha) annually since 2001 and is expected to continue to expand.