Geraldine House, a classroom block for year 7 and 8 pupils, remembers Sr Geraldine, the Anglican nun who came to Dunedin from England in 1896 to start the school and become its first principal.
It was officially opened yesterday by the Anglican Bishop of Dunedin, the Right Rev George Connor.
Pupils and parents gathered for a short chapel service before moving outside to watch Bishop Connor unveiling a plaque and cutting a ribbon.
The $2.5 million, two-storeyed building abuts the chapel and another classroom block.
It contains four classrooms, a teacher aide room and an archive room.
After the ceremony, principal Melissa Bell said the addition had been "phenomenally designed" to make the most of a small area of land previously used as a car park.
"We have ended up with a huge amount of space for very little loss of land."
Pupils moved into the new building a few weeks ago, she said.
The rooms they had vacated were being altered to provide much-needed administration space.
