2:13 to me looks like a Roman fortlet that would've housed scouts... considering the location and that it looks like it has at least 3 defensive ditches, it likely helped to protect the Maiden Way north of the Wall or a branch road from the Maiden Way. Although it could've been a Romano farmstead. As such, the stone circle remains would've been much older than the fort. It is pretty cool because the Maiden Way on the map appears to disappear at Bewcastle. It is scandalous what happened to our standing stones... the one at Nunwick Park (Simonburn) was supposed to be as tall if not taller than Duddo Stones and it was destroyed because it fell out of fashion to have a stone circle in your stately country park or the land owners got sick of people trespassing to see them. I always used to think that it was the cult of St Cuthbert that led to the destruction of pagan symbols in the borders... but now I think it was mostly a later 18th, early 19th Century Georgian/early Victorian disrespect for ancient monuments. Many of the stones would've been taken for gate posts and building materials... or indeed cleared to make easier use of the land.
A bi difficult finding a good description of a quadraburgis, his was the best I could find. Sources stated that they were on he order of 50 m square. www.persee.fr/renderIllustration/efr_0223-5099_1997_ths_229_1_T2_0062_0000_2.png
