Hmmm... looks like an old concrete pad on top of the mountain above Carreg Cennen castle is Im not mistaken. Im told they were placed there in WW2 for spotlights which were switched on when the German bombers came over to bomb Swansea. The comparitively crude nav aids used thought the lights on top of the mountain was Swansea - bombs were then dropped on top of the mountain hence all the bomb holes in the area! But then I could be wrong