Castle High School opened on 1st September 1985 when Dunlambert Boys’ Secondary School amalgamated with Graymount Girls’ Secondary School and Mountcollyer Secondary School. The new school was established on the Fortwilliam Park site of the former Dunlambert School, which was founded in 1958, and, at its peak, accommodated 1000 pupils.Dunlambert was officially opened the following year on March 1959 by the then Prime Minister of Northern Ireland, Lord Viscount Brookbrough. The founding Principal of Dunlambert was Samuel Lynn and the Vice Principal was Bill Singer. The last Principal of Dunlambert and the first Principal of Castle High was the well liked Bob Jones.

Website: http://www.castlehigh.ik.org/home.ikml