Why did Edward I build so many “state of the art” castles in northern Wales? Dr Sam Willis has described Edward I as,” the greatest castle building king this country has ever seen”. He went on to say, "his castles were his Arthurian Camelot, a tool to conquer and then recolonise". Dan Jones has commented, "every Plantagenet king with exception of Richard I has come to Wales and all departed having barely left a footprint. Edward I ended that trend emphatically".