Ballston is a neighborhood in Arlington County, Virginia. Ballston is located at the western end of the Rosslyn-Ballston corridor. It is a major transportation hub and has one of the nation's highest concentrations of scientific research institutes and research and development agencies, including DARPA, the Office of Naval Research, the Advanced Research Institute of Virginia Tech, the Air Force Research Laboratory, and engineering, management, and public sector consulting firms. Ballston also includes a section known as Virginia Square and sometimes the area is collectively known as Ballston-Virginia Square.

Arlington County, or simply Arlington, is a county in the U.S. state of Virginia. The county is located in Northern Virginia on the southwestern bank of the Potomac River directly across from Washington, D.C., the national capital.