An application for an auditorium plus music, art, maths, languages, economics and geography classrooms at the private school received the green light from councillors at a recent planning meeting.
A proposal to demolish the existing concert hall building and later extensions to the north building was also granted.
The concert hall building was originally built as a gymnasium in 1872. Under the plans, the existing north building will be refurbished to provide the new music courtyard, while the final phase involves the demolition of the old gymnasium to make way for a 270-seat auditorium and teaching spaces.
The plans were approved despite objections from heritage body The Cockburn Association.
In a letter to the city council, The Cockburn Association said it was “strongly opposed” to the plans.