Hammond Castle is located on the Atlantic coast in the Magnolia area of Gloucester, Massachusetts. The castle, which was constructed between 1926 and 1929, was the home and laboratory of John Hays Hammond, Jr. He was an inventor who was a pioneer in the study of remote control and held over four hundred patents. The building is composed of modern and 15th-, 16th-, and 18th-century architectural elements and sits on a rocky cliff overlooking Gloucester Harbor.