ATON: Aid To Navigation - could be lighthouse, lightship, buoy, etc.
Art, now that you know it's an ATON, it could be any one of 3.
My photos are things you find at a particular lighthouse. I blurred out part of the photo because it names the site.
In most cases, you'd have to have visited that lighthouse/lightship to recognize what's there. In this case, you've narrowed it down. Take a stab at one.