Look no farther than Fort Tilden in Queens' Rockaway Peninsula.
It's an old Army base, that is now part of the Gateway National Recreation Area.
The area was first used as a United States Army installation some time during the War of 1812 (1812 - 1815). It was turned into a fort base in 1917 during the First World War, and named after 1874 Democrat governor of New York, Samuel Jones Tilden. The area was also used as Naval Air Station Rockaway, which was the departure point for the first transatlantic flight in 1919 (by a Curtiss NC-4 flying boat), as well as the US/NATO missile sites Nike Hercules (aka SAM-A-25) and Nike Ajax (aka SAM-A-7). From 1966 to 1980, the site was used to house the Army Reserve Post for 411th Engineer Brigade, plus the 187th Infantry Brigade's 5/5th Field Artillery, which had 105mm howitzer cannons active (until 1995) upon Battery Harris West...
...and Battery Harris East, which now has a public viewing platform atop.
The fort was deactivated in 1974, and turned over to the National Park Service, but it wasn't until it was officially decommissioned in 1996 that the land was open to the public.
The area is now a popular spot for birdwatchers, fishermen, and graffiti artists.
It's a great place to check out some of the best up and coming artists in the New York City area, or just see the architectural future of mankind's retrogression.