Scale 1 inch = 40 feet. U.S. Engineer Office, New York, October 22, 1880. Sent to the Chief of Engineers with my report of this date. Q.A. Gillmore. Liut. Col. Of Engineers. Pvt. Maj. Gen. U.S.A.
LocationsCastillo de San Marcos National Monument, Saint Johns County, Florida, United States(29.89786,-81.31217)