Completed in 1955, the Colonial Mutual Life Assurance Building (Former) is a prominent commercial building within central Nelson. The Colonial Mutual Life Assurance Building has historic importance because it is associated with a longstanding company in New Zealand. This building was also part of a local mid-twentieth century building boom. The Colonial Mutual Life Assurance Building has architectural heritage value as an International Style building designed by noted architectural firm, Structon Group. This building is indicative of a range of influences informing the practice’s designs in this period. The Colonial Mutual Life Assurance Society (CML), established in 1873, was one of a number of life insurance companies operating in New Zealand in the late nineteenth century. Their main offices were in Auckland, Wellington, and Dunedin, but people in Nelson had access to their services from the 1880s through travelling and local agents. Nelson was the New Zealand Company’s second settlement. The site was chosen by Captain Arthur Wakefield (1799–1843) in 1841 and Trafalgar and Nile Streets were the first roads surveyed. As Wakefield intended, Trafalgar Street north of Church Hill became a predominantly commercial area. The intersection of Trafalgar and Hardy Streets was characterised by hotels from the 1850s, with the Masonic Hotel established on the northeast corner in 1850 and rebuilt several times. The hotel was demolished in April 1955 to make way for the CML’s new building. The building was designed by the Wellington-based Structon Group. This architectural practice was founded in 1944. Around the same time as their work on the Colonial Mutual Life Assurance Building they were involved in the Lower Hutt Civic Centre development, noteworthy for its modern movement architecture. On a prominent corner site, Colonial Mutual Life Assurance Building seems architecturally conservative for its time and within the oeuvre of Structon Group, showing International Style influences which include a largely austere exterior interplaying sharp edges and curved surfaces. The central tower’s vertical fin detailing was originally the background for the building’s name. The tower’s mushroom-shaped cap provides a space-age reference. The verandah wrapping around the building’s street fronts was an original/early feature. This period seems to have been one of economic growth in Nelson, with new buildings ‘popping up all over town’. For example, plans for Christ Church Cathedral were approved in 1957 and other buildings and structures on the New Zealand Heritage List/Rārangi Kōrero were built, such as the New Zealand Insurance Building. Some of the building resulted from emergencies, such as the flood which led to the Collingwood Street Bridge’s construction. The local radio station, 2XN, broadcast from the Colonial Mutual Life Assurance Building during 1966 while a replacement was being built for its former home, destroyed by fire. CML’s business appears to have been growing too, because Structon Group were also commissioned to design their Lower Hutt offices. This building, completed in 1957, is architecturally similar to its Nelson counterpart but on a larger scale. CML is now part of the Sovereign Group (2016) and sold their Nelson building in 1983.