It was located in Fortwilliam Park, and was within the Belfast Education and Library Board area.
[citation needed] Castle High School was the beneficiary of a remarkably historic site: within the school's 8-acre (32,000 m2) grounds are the Celtic and Anglo-Norman remains of an original Dun, or fort, flanked by a prehistoric souterrain.
[citation needed] On 23 June 2008, Castle High School held a celebration to mark 50 years of education at its current site at Fortwilliam Park in north Belfast.
The event was hosted by the BBC journalist and broadcaster Dr William Crawley, a former pupil of Dunlambert School, with musical performances from the Belfast School of Music's Concert Band.
[citation needed] From 1 September 2009 the building was used by the Belfast School of Music and is the site of offices for the Education Authority.