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 the vast majority originating from Washington Metro stations. Arlington is served by the Orange, Blue, Yellow, and Silver lines of the Washington Metro. The Metro stations in Arlington are the only stations outside of Washington, D.C. where the system's original Brutalist architecture can be found. Additionally, Arlington is served by Virginia Railway Express commuter rail, Metrobus (regional public bus), Fairfax Connector (regional public bus), Potomac and Rappahannock Transportation Commission (PRTC) (regional public bus), (DASH bus) (regional public bus) and a county public bus system, Arlington Transit (ART). Metroway, the first bus rapid transit (BRT) in the D.C. area, is a