Derwen Bedwen (with Cob Walls), Cnwch Coch, Ceredigion 2010 The "unknown farm building with cob walls!" is called "Derwen Bedwen". It stands by the road between Cnwch-coch and Llanfihangel y creuddin, and was last lived in by a woman named "Marged Lizzie" untill the late sixty's. She had two or three nasty dogs that always chased us as we walked past on the way home from school!