Castlereagh (County Down townland)

54°34′38″N 5°53′18″W / 54.5771795°N 5.88821°W / 54.5771795; -5.88821 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).