Fort Jay is the coastal Star Fort and the name of the former Army Post (notice its star shape) that was located on Governors Island. It opened in 1808 and was built to defend Upper New York Bay.Castle Williams is the circular fortification on the northwest point of Governors Island, part of a system of forts constructed in the early 19th century to protect NYC from a naval attack. It opened in 1811. In 1964 the United States Army closed its First Army Headquarters there and turned it over to the US Coast Guard who used it until 1996. It was subsequently turned over to the now present National Park Service.