Tre'r Ceiri hillfort on a plateau on one of the peaks of Yr Eifl mountain, overlooking the fishing village of Trefor, near Caernarfon. it is constructed of dry stone walls from the stones found on the mountain's scree. There are in the region of 150 stone hut circles dating back to the Iron Age and there are two entrances, this being the western entrance. Photo taken 22 December 2009.