Arsenal Penitentiary

The Arsenal Penitentiary was a penal institution in Washington, D. C. used as a military prison during the American Civil War, currently located inside Fort Lesley J. McNair.

Four Lincoln assassination conspirators, David Herold, Lewis Powell, George Atzerodt, and Mary Surratt were executed on the grounds of the Arsenal Penitentiary on July 7, 1865.

It was designed by Charles Bulfinch and constructed adjacent to the north side of the Washington Arsenal separated by a wall.

[1][2] During the Civil War, the penitentiary was closed in September 1862 to store munitions on the request of the Ordnance Department.

[3] It was reactivated as a military prison in April 1865,[4] and it was where eight Lincoln assassination conspirators were held, put to trial, and four of them were executed.