Bedd yr Afanc means ‘grave of the water monster’. This area is full of streams, and the water monster used to live in a pool near the bridge over the Brynberian river. The local people didn’t like him for some reason, so he was killed and buried in this mound. The long low oval mound/cairn is a ‘gallery grave’. No capstones survive of the chamber, but you can see a long low passage of ten pairs of ~50cm uprights leading to a small circular chamber made by seven stones. The site nestles below the Preseli Mountains, where the bluestones for Stonehenge originated.