Hidden history

History never rests, it's always creating more of itself, so much so that most of what went before gets forgotten, especially the ephemeral.  We'll walk past historical hints all the time, totally oblivious to them or the parts they played. Take these iron loops on one of our local bridges, two pairs a meter of so apart, set into the bridges brickwork opposite each other, easily overlooked. Any ideas about what they could've been for? The only reason I know is that one of my archaeological interests are the home front defences/sites/features of World War 2. These are anchoring points for wire anti tank/vehicle obstacles erected during the early part of the Second World War, the invasion fear period, probably by local defence forces. Who'd have thought. They reckon this sort of defence would've been effective in at least slowing down the light armour the Germans would have been able to land, and stopped most other vehicles. I understand there was some kind of defensive structure covering the bridge too, possibly a pillbox or strong point, although no evidence of that endures. Everything out there tells a story, and everywhere has stories to tell.