According to a letter to the editor in the Washington Post on Aug. 13:
http://washingtonpost.com/wp-dyn/opinion/A2495-2001Aug12.html
Ruth Lincoln Kaye [letters, July 28] raised concerns about the District boundary stone in Alexandria's Jones Point Park. The Wilson Bridge Project is taking steps to ensure this remarkable artifact remains not only part of our past but also part of our future.
The cornerstone marks the location George Washington designated as the southernmost point of the District. It was placed in 1791 under the order of Benjamin Banneker, an African American who was one of the primary surveyors of our nation's capital. Unfortunately, the stone's significance is largely unknown because it is difficult to get to and it is enclosed in an unmarked concrete bunker.
Although the new bridge will be more than 400 feet away, and construction will not approach the site, the Wilson Bridge Project, along with the National Park Service and the Mount Vernon Chapter of the Daughters of the American Revolution, is doing riverbank improvement, seawall repair and landscaping adjacent to the Jones Point Lighthouse where this stone is located. The vault in which the cornerstone sits will be rebuilt to increase airflow and to decrease the deterioration rate of the stone, which now is eroded by the Potomac River. Visits to the landmark will be enriched by improved access, signs explaining the stone's historic significance and a replica that will be placed close by the stone but in a more visible location.