Possibly an earlier iron age hillfort -- above the ithon in radnorshire, wales.
The first masonry caste at the site was constructed around 1242 to control several routes
through the welsh marches. cafnllys became a source of friction between Llywelyn ap gruffudd and roger mortimer in the prelude tp edward i's conquest of wales.
The castle was captured and razed in 1262 by Llywelyn, during a war with henry lll of england, and cefnllys featured prominrntly in the ensuing peace treaty. the construction of a new castle was a contributing factor to Llywelyn's refusal to swear featly to edward in 1275. leading to war in 1276.