In 1792, surveyor Andrew Ellicott and astronomer Benjamin Banneker, at the request of President George Washington and Secretary of State Thomas Jefferson,  used 40 limestone markers to carve out a  40-square-mile area between Maryland and Virginia to create Washington, D.C.

Last Saturday, the Daughters of the American Revolution and Masons from  the Most Worshipful Prince Hall Grand Lodge of Washington gathered around one of those well-protected  stones in Southeast Washington for a rededication ceremony, to recognize what they say is really the city’s oldest monument.

“These stones are our nation’s oldest national landmarks that were placed by  Andrew Ellicott and Benjamin Banneker,” said Sharon K. Thorne-Sulima, regent for the Martha Washington Chapter of the D.C. Daughters of the American Revolution. “They officially laid the seat of government of our new nation.”

George Washington, after Congress passed the Residence Act of 1790, established a 100-square-mile site for the national capital along the banks of the Potomac River from Alexandria, Va., to the south to Williamsport, Md., to the north.

There were originally 40 stones around the District of Columbia, and 26 are currently being preserved by the D.C. Department of Transportation and the National Park Service, said Thorne-Sulima, who added that the fact that the boundary of the District of Columbia is shaped like a square is not an accident.

“When Pierre L’Enfant laid out the District of Columbia, he called on many of his friends who were Masons,” said Thorne-Sulima, who also noted the fact that laying out the city brought together men of different races.

Most Worshipful Grand Master Norman L. Campbell of the Most Worshipful Prince Hall Grand Lodge said: “It is very important that the Masons be involved in this event. We have been in every war that has ever been fought and we have been involved in not only in the construction of the United States but things around the world.”

During the rededication, a Masonic chaplain offered a prayer that included,  “Dear Heavenly father, let  this ceremony be symbolic of the living stones and be set among the other stones that provide a solid foundation for those who are yet to come.”

David D. Baker, the Most Worshipful Grand Lecturer for the Most Worshipful Grand Lodge, conducted the ceremony, in which corn, wine and oil were poured on the stone that had 1792 carved on the side. Following the service, Baker said, “These are important stones and this is an important moment for our history.”

CORRECTION: The title for David D. Baker was incorrect in an earlier version of this article. It has been corrected.