It may occupy the centre of a pre-Christian cult associated with a great tree. By the time it was attacked and burned by the Vikings in 825 it had grown considerably in size and had extensive craft workshops creating a wide range of bronze, glass and other products. In 1135 Saint Malachy of Armagh introduced the Augustinian Canons. The graveyard contains many old (including one pre-Norman) graves, as well as the more modern ones including that of Colonel Paddy Mayne.