Fort Casey was one of three similar gun emplacements built at the turn of the 20th Century to guard the entrance to Puget Sound. The gun battery is recessed below the crest of a high bluff overlooking Admiralty Inlet. The 10-inch cannons were mounted on a carriage system that allowed them to rise up to fire and, using recoil energy, drop down out of the line of fire for reloading. https://en.wikipedia.org/wiki/Fort_Casey

I visited early on a foggy morning which provided an atmosphere that conveys the era and mood of the installation.