Benjamin Banneker: SW 9 Intermediate Boundary Stone, also known as an Intermediate Stone of the District of Columbia, is a surveyors' boundary marker stone, along what was once a boundary of Washington, DC, and now marks part of the boundary between City of Falls Church and Arlington County, Virginia. It is within Arlington County's Benjamin Banneker Park at the corner of North Vanburen Street and 18th Street North. It was named and was declared a National Historic Landmark in 1976 at the instigation of the Afro-American Bicentennial Corporation to honor Benjamin Banneker, who assisted in the land surveys that laid out Washington's boundaries. The stone was the first of the District of Columbia boundary markers to be listed on the National Register of Historic Places.