This is a diagram of the Fire Control Station on Diamond Head that was completed in 1910, prior to World War I. It was part of the Island's coastal defense system. It was an observation post for spotting enemy ships that approached O'ahu. Artillary spotters used triangulation to pinpoint enemy targets since they didn't have radar and modern computers. After hiking up Diamond Head on the trails, tunnels and stairs we approached this. We walked where the red arrows are in this picture.