The school occupies a estate in east Belfast, close to the Parliament Buildings at Stormont. All the school's facilities are located on this site, which also contains a small lake and forest named Netherleigh. Campbell's junior school – formerly located on an adjacent site and called Cabin Hill – is now also located on the site. The school has the oldest Combined Cadet Force in Ireland, with over 400 cadets. The school has an international reputation and attracts boarders from all over the world. Past pupils of the school are known as Old Campbellians or OCs and the school has an extensive past pupil organisation known as The Old Campbellian Society which has several branches across the United Kingdom, USA and Asia as well as regular OC reunions at the school itself. The school colours are black and white, whilst the OC colours are black, white and green.