This caisson light was commissioned in 1891 to mark the Middle Ground shoal in one of the busiest shipping channels of the Bay. The caisson and tower stand approximately 45 feet above the water. The light was automated in 1954 and is still active. In addition to the nearby Navy base, commercial ports, shipyards, and drydocks, this location is also famous for first battle between two ironclad warships, the U.S.S. Monitor and C.S.S. Virginia (a.k.a. Merrimack) during the American Civil War.