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.
At present, the castle operates as the Hammond Castle Museum, displaying Hammond's collection of Roman, medieval, and Renaissance artifacts as well as exhibits about his life and inventions. The Great Hall contains a huge pipe organ which has been used for concerts and recordings by many famous organists including Richard Ellsasser and Virgil Fox.