Governors Island, Castle Williams, New York Harbor near Hay & Andes Roads, New York, New York County, NY

Significance: Castle Williams, a three-tiered, circular, casemated fortification built between 1807 and 1810/11 served as a prototype for a new era of coastal fortification. Its massive masonry walls and design by American military engineer, Lieutenant-Colonel Jonathan Williams, were typical of fortifications erected in the years prior to the War of 1812 in what became known as the Second American System of fortifications. Williams was the Army's Chief Engineer and first superintendent of the Military Academy at West Point. At the time it was constructed,the Castle, which had the capability of mounting slightly over 100 guns, was one of the largest works in the defense system that effectively protected New York City and its harbor during the War of 1812. Today, it remains as one of the country's best preserved fortifications of its type.
Unprocessed Field note material exists for this structure: FN-365, FN-366
Survey number: HABS NY-5715-2
National Register of Historic Places NRIS Number: 85002435