Reading the guide to The Cross Britain Way I noted reference to an ER marked by the careful planting of trees on the top of Beacon Ring Iron Age Hill Fort just inside the Welsh border near Welshpool.
There is also an ER on the hillside at Chatsworth Park and this one is visible to passing walkers the one at Beacon Ring is only visible from the air.
We now have the benefit of online aerial images so they can be viewed here.
Beacon Ring (opens a new window)
Chatsworth Park (opens a new window)
Do you know of any more? Submit your links in the comment box below.