Castle Clinton or Fort Clinton is a circular sandstone fort, now a national monument in Battery Park at the southern tip of Manhattan.
Military - Historic - Forts and Batteries
Construction began in 1808 and was completed in 1811. The fort, known as West Battery (sometimes South-west Battery), was designed by architects John McComb Jr. and Jonathan Williams. It was built on a small artificial island just off shore.
West Battery was intended to complement the three-tiered Castle Williams (still extant) on Governors Island, which was East Battery, to defend New York City from British forces in the tensions that marked the run-up to the War of 1812, but never saw action in that or any war. Subsequent landfill expanded Battery Park, and incorporated the fort into the mainland of Manhattan Island.