The Colonial Ammunition Company Shot Tower is the only twentieth-century shot tower in Australasia, and a rare example internationally to have been built using steel-framed construction. Erected about 1916, the tower was designed to manufacture lead shot for shotgun cartridges, which were employed for sport and hunting. The structure was part of an extensive industrial complex in suburban Mt Eden, Auckland, established by the Colonial Ammunition Company (CAC) in the mid 1880s as the earliest munitions factory in Australasia. The CAC had been partly founded in response to a feared Russian invasion of New Zealand, and later established a factory in Footscray, Melbourne. Producing mainly military ammunition, its early manufacture of shotgun cartridges at Mt Eden was small-scale using shot made in the South Island. As demand for its miltary products grew during the First World War, the company set out to compete with the British-made imports that supplied most of the 9 million shotgun cartridges used annually in New Zealand. The shot tower was constructed against the wishes of the CAC head office in England, but allowed production levels at the factory to remain high after the war had ended. Approximately 35 m high, the tower consists of a polygonal room clad in corrugated iron, supported on a steel frame. The structure was built by local blacksmiths, W. Wilson and Company and initially operated by a Mr Lylie and his two daughters, who had previously supplied the factory with a limited amount of shot from Nelson. Shot was made by passing molten lead through a sieve at the top of the tower, which solidified as it fell into a water-filled pit in a room at its base. The shot was then polished, graded and stored in associated corrugated iron structures attached to the tower, and recycled if found to be imperfect. The tower and its related structures were altered as aspects of shot production progressed, until the CAC vacated the site in the 1980s. The buildings at its base were demolished in 2001, although the tower remains after a popular outcry to save it. The shot tower is of national and international importance as the only remaining shot tower in New Zealand, and the only one of steel-framed construction believed to exist in the Southerbn Hemisphere. It is of great importance for its connections with the Colonial Ammunition Company, which was the earliest producer of ammunition in New Zealand and Australia. The tower is significant for demonstrating local resourcefulness in its construction, and is associated with increasing confidence in local manufacturing during the First World War and the early years of the Dominion (1907-1947). It is a reminder of the country's involvement during the First World War and its tradition of hunting and shooting for sport, which directly stems from its colonial and Maori past. The tower demonstrates aspects of production technology that had changed little from the 1780s, as well as working conditions for both male and female employees in the early twentieth century. It is also valuable as a highly visible and distinctive landmark, which reflects the industrial history of the local area.