Cefn Bryntalch is an earthwork castle formed by adapting a ridge-end position above the Severn to produce two enclosures. The lower of these, c.40m by 20m, embanked and with a causewayed entrance, is open towards an upper work, c.28m by 20m, itself completely embanked. The whole is ditched about with a counterscarp, c.155m by 76m overall.
