http://en.wikipedia.org/wiki/Sandy_Hook
Sandy Hook National Park is a spit of land that sticks out into the New York Bay shared by Staten Island, New York. As such, it was during times of war a vital location for defense of this country's maritime border.
Fort Hancock is a decommissioned Army post that had live defenses built into the sand, but also was an artillery test range. Large guns, firing ten and twelve inch rounds, were fired down the beach to measure speed and accuracy.
Much of the original installation is there for the public to see, minus the guns themselves. The concrete bunkers and mounts have largely been hidden by sands and trees, but the park has also made them accessible via a network of paved trails. Signs and old photos are posted with information about the Army's mission.
I went here twice, once by myself on what turned out to be a very rainy evening, and again with my workmates. On that second trip, we parked at the first lot and biked the park from end to end.
After that we had a fantastic dinner of fresh seafood at a local restaurant. Good times!