n.
Unincorporated settlement (pop., 2000: 189,453), northern Virginia, U.S. Lying across the Potomac River from Washington, D.C., the city is the capital of Arlington county, which was part of Washington, D.C., from 1789 to 1846, when it was returned to Virginia.
It is the site of Arlington National Cemetery (located on the former estate of Robert E. Lee ), Ronald Reagan National Airport, and numerous federal buildings, including the Pentagon .