According to the Wikipedia article, “Sagamore Hill Military Reservation was a coastal defense site located in Sagamore Beach, Massachusetts. Today, the site is the location of Scusset Beach State Reservation. Sagamore Hill Military Reservation was built on state land. Its mission was to protect the Cape Cod Canal from possible air and naval attack. It never did have to fire its guns in defense but did play an important part in the defense of the canal. The Panama mounts (1942) and battery commander’s station of a two-gun 155mm battery still remain here, as well as several magazine igloos.”

Location: Google Maps (41.780782,-70.516720)