"The boundary stones are the oldest federal monuments. The Residence Act of July 16, 1790, as amended March 3, 1791, authorized President George Washington to select a 100-square-mile site for the national capital on the Potomac River between Alexandria, Virginia, and Williamsport, Maryland. President Washington selected the southernmost location within these limits, so that the capital would include all of present-day Old Town Alexandria, then one of the four busiest ports in the country. Acting on instructions from Secretary of State Thomas Jefferson, Major Andrew Ellicott began surveying the ten-mile square on February 12, 1791. In 1915 the District of Columbia Chapters adopted the Boundary Stones, acquired deeds from the property owners to install a footing for the iron protective fences." They had identical fences designed and installed and finally in 1916/1917 dedication ceremonies took place to mark each stone with a plaque with the name of the Chapter who agreed to be its steward. (Wording from www.boundarystones.org).