Castell-y-Bere is located some 7 miles from the town of Tywyn and just down the road from the Llanfihangel-y-Pennant. The outcrop of rock that Llewelyn ap Iorweth chose to construct his castle in 1221 is a glacial feature called a 'roche moutonnee', located on the floor of a typical 'U'-shaped glacial valley.