The cornerstone was laid by president of the United States George Washington Leder of the Lodge of the Continental Army, assisted by the Grand Master of Maryland Joseph Clark, in a Masonic ritual.

Many of the items of ritual paraphernalia used in the cornerstone ceremony have been repurposed and are currently used for the placement of foundation stones at other important buildings in the greater Washington area.

During construction of the foundation, building commissioner David Stuart wrote to other members of the capitol commission suggesting a cornerstone ceremony be held.

[1][2] At 10:00 a.m. on September 18, President of the United States George Washington and his Masonic entourage crossed the Potomac River to arrive in Federal City (District of Columbia).

There, they were joined by an escort consisting of the Alexandria Volunteer Artillery, and members of Masonic lodges from Virginia, Maryland, Georgetown, and Federal City.

"[1] Washington, accompanied by three Worshipful Masters carrying sacrifices of corn, wine, and oil, then struck the stone three times with a gavel, as prescribed by Masonic custom.

Washington exited the trench to ritual chanting by the assembled Masons and a 15-gun salute (one gun for each U.S. state) from the Alexandria Volunteer Artillery.

[7][8][9] The precise location of the cornerstone was lost during the two centuries following the ceremony due to attack and multiple expansions of the original building.