Two Oamaru stone finials, decorative columns topped by a stone ball, were yesterday being re-installed on the front of the building.
The finials will have stainless steel rods inside to make them safe during an earthquake.
The 120-year-old Victorian-style courtyard facility designed by John Campbell, who also designed the neighbouring courthouse building, was decommissioned in 2007.
The Dunedin Prison Trust took on the building and raised about $500,000 to start the first stage of its development programme to return it to its original appearance.
Part of that work is to replace decorative architectural elements removed from the front of the building.
Architectural conservator Guy Williams said he found the base of the finials behind panelling in the attic of the building, allowing him to re-create the rest based on a photograph from its heyday.
Stonemason Marcus Wainwright said the two finials had begun the work to add the decorative pieces, with more to come soon.
