Bangor Monastery (600)
Old manuscripts report that there was a very large monastery close to the River Dee, but nobody has found any trace of it to date. Also, they report that the Northumbrian King who won the battle of Chester at the turn of the tenth century, slaughtered 1,200 monks from Bangor because they prayed to their God for the wrong side to win the battle. There is no factual proof that this happened and there are doubts over the even because of the vast number of monks mentioned.