caer drewyn iron age hillfort corwen wales

caer drewyn iron age dry stone rampart ramparts hillfort hillforts hill fort forts fortress defence defensive wall walls clwydian range dee valley vale edeyrnion area outstanding natural beauty aonb ancient monument ruin ruins landmark history historic historical site points interest landscape travel culture heritage corwen denbighshire north wales welsh british great britain united kingdom owain 1400 glyndwr dated 500 bc reputed believed based army