Original: They are found in Northern Europe, especially in Ireland. In Irish language sources they are known by a number of names: rÃ th (anglicised rath), lios (anglicised lis), caiseal (anglicised cashel), cathair (anglicised caher or cahir) and dÃ n (anglicised dun or doon).
Simplified: A rÃ th (anglicised rath), was made of earth, caiseal (northwestern Ireland, anglicised cashel) and cathair (southwestern Ireland) were built of stone.