Looking down from Peel Crags.A bizarre location for a turret as it can be overlooked from the crags and from Steel Rigg,off image to the rhs.Also,unusual.The turrets tended to be laid out when the base course was laid,often well ahead of the main wall construction.In this example,the turret has been built adjoining the back of the wall.Rare!More usually see http://www.pbase.com/taggart51/image/71642771
see http://www.roman-britain.org/frontiers/hw_guide.htm