Arlington County, Virginia area. The county is situated in Northern Virginia on the southwestern bank of the Potomac River directly across from Washington, D.C., of which it was once a part. With a land area of , Arlington is the geographically smallest self-governing county in the U.S., and by reason of state law regarding population density, has no incorporated towns within its borders. Due to the county's proximity to downtown Washington, D.C., Arlington is home to many important installations for the capital region and U.S. government, including the Pentagon, Reagan National Airport, and Arlington National Cemetery. Many schools and universities have campuses in
Arlington County, Virginia Arlington helps provide Catholic education in northern Virginia, with early learning centers, elementary and middle schools at the parish level. Bishop Denis J. O'Connell High School is the diocese's Catholic high school within Arlington County. Marymount University is the only university with its main campus located in Arlington. Founded in 1950 by the Religious of the Sacred Heart of Mary as Marymount College of Virginia, both its main campus and its Ballston Center are located on North Glebe Road, with a shuttle service connecting the two. George Mason University operates an Arlington campus in the Virginia Square area between Clarendon