Located near the middle of Whidbey Island, Fort Casey was built in the late 1800s, and other than some antiaircraft artillery, few major installations were added after the initial project. Armament at the fort included sixteen 12-inch mortars, seven 10-inch disappearing guns, six 6-inch disappearing guns, two 5-inch guns and four 3-inch guns.
Southern Fort Casey is now a state park, while the northern parts (including Battery Parker) are owned by Seattle Pacific University.
Batteries Moore, Parker and Valleau's interiors are closed, along with parts of the mortar batteries. A few of the FC stations are closed as well.