Construction of the courthouse began in 1864 and progressed well until heavy rainfall in the Autumn unsettled the foundations and caused the cupola to lean dangerously. By August 1865, the building was 'nearly completed' and Council proceeded to purchase stoves and furniture. Occupancy occurred in December 1865.

The County Courthouse was designed to accommodate the needs of both government and justice, dual functions which it continues to serve to this day. A mixing of Palladian and Italianate architectural details, worked in local limestone, suitably expressed the building's stately function.