Wedged between Maryland and Virginia, the District of Columbia was established in 1790 to serve as the permanent seat of the U.S. federal government. Originally the territory was relinquished by Virginia and Maryland as a 100-square-mile plot on both sides of the Potomac River. At the time, Georgetown, Maryland, and Alexandria, Virginia (just out of the scene to the lower left), were successful ports located on the eastern and western sides of the river. Georgetown remains as an historic neighborhood of Washington, D.C. In 1846, Virginia gained back the land contributed to the District of Columbia as a result of neglect of the area by Congress (known as retrocession). Those areas eventually became the cities of Arlington and Alexandria. There are 40 boundary stones that mark the original District boundary and stand as the oldest federal monument in the country.