Castlereagh (County Down townland)
Coordinates: 54°34′38″N 5°53′18″W / 54.5771795°N 5.88821°W Castlereagh (from Irish: An Caisleán Riabhach, meaning "the grey castle") is a townland and former hamlet in the civil parish of Knockbreda, barony of Castlereagh Lower, in County Down, Northern Ireland. It is southeast of Belfast and now at the fringe of the city's suburbs. The townland has an area of 415 acres (168 ha).
About 1350, at the site of a rath in the Castlereagh Hills, Aodh Flann O’Neill is said to have built the castle from which the townland was named. Aodh was of the Clandeboye, a branch of the O'Neill dynasty who colonised the area from the west.Con MacShane O'Neill raided Belfast from the castle after Christmas 1602, leading to retributions from the Elizabethan settlers there. In 1615, he was reduced to selling the manor comprising the castle and grounds to Moyses Hill, ancestor of the Marquesses of Downshire, who still exercised jurisdiction there in the 1840s. The castle was ruined by the 1750s.
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