In 1864 work began on the pink dolomite stone Courthouse and was completed in 1878.
Mount Gambier Court House was opened in 1865. It served as the district court until new premises were constructed across Bay Road in 1974-5. It is an imposing building and it reflects the formal architectural style of important government buildings of the 1860s.
The Mount Gambier Court House is a landmark building, designed by George Thomas Light, the assistant colonial architect, and constructed of local pink dolomite. The design for the Court House was a strictly symmetrical masonry building with a central double height section, flanked by single storey wings of one room depth. The detail was simple but appropriate to the form of the building.
The Court House was completed in June 1864. The building consists of a large central court room 36 feet by 26 feet, with four auxiliary offices and a cell. Each room has direct access to the court room, but no access to each other. The rooms are mostly furnished with original furniture.
There are established displays, information and interpretive banners which tell the stories of some of the people who worked at the courthouse or whose crimes were judged there.