The Southland Provincial Council building, by virtue of its long, varied history and its attractive, well proportioned façade is one of the most important historic landmarks in Invercargill.
Built in 1864 for the Masonic Lodge, it was just two years later that the newly formed Southland Provincial Council bought the building to use for its own meetings. Four years later, the Otago and Southland provinces were reunited and the building brought under the Otago Government's jurisdiction.
From 1870 until 1879, the Supreme Court had sittings in the building and alternated with the Invercargill Borough Council which had been formed in 1871. To accommodate the growing staff of Invercargill Borough, the Council extended the building in 1900 but this part was later demolished. The council remained in the chambers until 1959. From this time, it has been used for a variety of purposes. The NZHPT bought the building in 1979.
Architecturally the building is a classical structure built of brick with plaster exterior and interior. Inside there is the main debating chamber and two small rooms, one on either side of a small entrance hall. The classical façade features a pediment consisting of a simple cornice with dentils beneath, atop a solid one-storey structure. There are plaster quoins at the corners of the façade and dressings on either side of the entrance alcove imitating quoins. On the façade there are two round headed windows with recessed columns on either side of each and vermiculated key-stones in the arches.
As one of the oldest surviving Masonic Halls and one of only two surviving Provincial Government buildings, the Kelvin Street Chamber is Invercargill's most historic building.