The Cargill’s Castle Trust chairman said subject to funding, work to stabilise the historic building was set to begin in the first half of 2024.
"For a long time, we’ve been treading water and waiting for things to open up again after the Covid-19 pandemic.
"The project is finally starting to go places."
The Dunedin City Council granted building consent earlier this year, to begin stage one of a development that will eventually turn the decaying building into a major tourist attraction.
In stage one, steel bands (plates) would be placed around the top of the walls to stabilise and strengthen the building.
Mr De Graaf said he was relishing the moment when the first plates were bolted on to the building.
"It’ll be good just to get started and stop any more deterioration and protect it for the long-term."
He said about $300,000 was needed to complete stage one and the trust had already raised more than a third of that amount.
"We like to think that once we get the first stage done, we’ll get a bit of momentum and things will start snowballing from there."
Then in stage two, floors, stairways and viewing platforms would be created, and cracks in the walls would be filled.
He said the plan was to have a metal walkway in the building, and stairs which tourists could walk up so they could see the views over the city and down the Otago coastline.
Overall, the project was expected to cost up to $2 million, he said.
The Italianate mansion was built for Edward Cargill, designed by Francis Petre and built by Harry Lyders. It was completed in 1877.
Fire gutted the building in 1892, but it was restored by Cargill and had several owners after that.
It was vacated by its last owner in 1973 and now lies in ruins.
Mr De Graaf hoped the building would be completed and reopened to the public by 2027, 150 years after it was built