see http://www.castlewales.com/sknfrth.html
see http://www.ecastles.co.uk/skenfrith.html
see http://www.castlexplorer.co.uk/wales/skenfrith/skenfrith_photos.php
Quite curiously,the round keep was built on a level surface,having earth piled up against it afterwards,to give the effect of having been built on a motte.