The oldest Christian site in Mourne is the little graveyard near the mouth of the Cassy Water in the townland of Lisnacree and was first approached by sea. Here St Tuan is said to have founded a church in the fifth century. Known as the Tamlacht (plague monument), it was in medieval times, a chapelry attached to Kilkeel. Here, the mother church of Mourne, dedicated to St. Colman (6th century), was built inside a rath of which the remains can still be traced. Also whose curving wall faces the main road leading into Kilkeel from the north-east to swing round sharply before it drops to the river crossing.