The Highlands Center at the Cape Cod National Seashore is the site of the former North Truro Air Force Station. The station was active between 1951 and 1985.
More information: Brochure
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)
The Three Sisters were lights build around 1837 to mark the dangerous Nauset sand bars off of Eastham. They were replaced in the 1920s by the current Nauset Light which is still in operation today. The Three Sisters can still be visited, however, preserved in a clearing near the Nauset Light. More information can be found here.
Location: Google Map
Day and night photographs of the Nauset Lighthouse located on Cape Cod in Eastham, MA. More information can be found here.