I’am mentioning this because it was the centre for the early Church in Mourne, dedicated to St. Colman in the 6th Century, now derelict.
But more importantly, it was built inside a Rath, of which the remains can still be traced and whose curving wall forces Newcastle street to swing round sharply before it drops to the river crossing.
Note: There is an abundance of Raths or Ring-Forts sites in the plain of Mourne. My count is of 56 sites, although many have been partially or completely destroyed. They are known locally as Forths.