A museum first opened to the public in Canterbury in 1867 in the Canterbury Provincial Council Chambers. It soon became obvious that the small space allocated to this building was insufficient and the Provincial Government put aside a sum of money at the end of 1868 for the construction of a specific museum building. Julius von Haast (1822-1887), the former Provincial Geologist, became the first director of the museum and it was his exchanges of native bird skins, Maori artefacts and moa bones for other objects with overseas museums that allowed Canterbury to rapidly build up an impressive collection.

Von Haast had been agitating for a museum since 1862 and in 1864 the Canterbury Provincial Council invited architects to enter a competition for a new museum building. Six entries were received, and of these none fulfilled the Provincial Council's request that an initial portion be able to be constructed immediately for £1,000. Despite this difficulty two proposals, those by Robert Speechly and Benjamin Woolfield Mountfort (in partnership with Maxwell Bury), were accepted for consideration and the £50 prize was split between them.

Construction of the new museum did not begin at once. It was said that this was because neither Speechly's nor Mountfort's designs could be built in stages. However, architectural historian Ian Lochhead argues that this was a delaying tactic by the Provincial Council rather than a legitimate reason for not beginning construction. As the collection continued to grow Haast pleaded for a temporary building and the Provincial Council agreed to build one in brick, designed by the Provincial Engineer, Edward Dobson.

Mountfort, however, reminded the Council that his design had been one of those selected and he provided plans for a stone building which could be erected for little more than Dobson's brick building would cost. His proposal was accepted and work began on the first building for the museum. The design of this building went through a number of revisions, finally being resolved as a building rectangular in plan, with a first floor gallery. Office space was provided in a timber lean-to attached to the north end. While the exterior of this building was described as 'plain' the interior was more dramatic. Timber columns ran from floor to ceiling and supported a gallery at the first floor level. The roof was constructed from massive timber arches supporting a glazed ceiling that provided 'a beautifully broken, silvery light over all the building...'. (cited Lochhead, 1999: 267)

This building opened to the public in 1870. By the next year it already was proving too small and tenders were called for an extension. The new wing, also designed by Mountfort, ran at right angles to the first and had a more ornate exterior.

In 1876 construction began on the third stage of the museum building, again designed by Mountfort. This extended the 1872 wing eastwards and then ran parallel to the 1870 building, forming a U-shaped courtyard that was open to the north. The exterior of the 1876-1877 wing was again more elaborately decorated, and featured both a square tower and a fleche. Mountfort's biographer, Ian Lochhead describes the elevation on Rolleston Avenue as an eclectic mixture of sources, both modern and medieval, with the design of the entrance porch being drawn more directly from George Edmund Street's Church of St John the Evangelist, Howsham, Yorkshire.

The final nineteenth century addition to Canterbury Museum was again designed by Mountfort and opened in 1882. Mountfort enclosed and roofed the north end of the courtyard between the 1870 and 1877 wings to provide a large amount of additional display space. The timber trusses of the roof spanned 48 feet (14.6 metres), which Lochhead states 'represents a considerable nineteenth century engineering feat, creating one of the most impressive interior spaces built in nineteenth century New Zealand'. (This space was considerably altered by the addition of a mezzanine floor in 1994.)

As part of the construction of the 1882 addition it appears that the whare whakairo, Hau-te-Ananui-o-Tangaroa from Tokomaru Bay,was moved from the courtyard, where it had been erected in 1874, to the western side of the 1870 wing. This whare had been acquired by the Museum in 1873 from Henare Potae, a Ngati Porou rangatira. The components of the whare arrived in Christchurch in early 1874 along with two carvers, Hone Taahu and Tamati Ngakaho, who spent the remainder of the year carving and erecting Hau-te-Ananui-o-Tangaroa. The whare whakairo was dismantled in 1955 and is currently in storage.

Subsequent wings were added in 1955-1958 (the Centennial Wing) and in 1977 what became known as the Roger Duff Wing was opened. During the 1990s a four storey block was built on the courtyard that had been created by the construction of the 1950s and 1977 wings. These are not included in the registration.

The Canterbury Museum is the oldest purpose-built museum building still in use in New Zealand. Historically it illustrates the Victorian concern with the classification and recording of the world, and the importance that the new institutions of museums were given as places of learning. Mountfort was involved with the construction of the museum for seventeen years and the nineteenth century portions are a fine example of his work and of Gothic Revival architecture generally. The museum forms a prominent part of the surrounding townscape, which includes the Gothic revival buildings of the Arts Centre and Christ's College, and of the Botanic Gardens.