The first Post Office in Christchurch was sited in Market Square, now known as Victoria Square. The Chief Post Office in Cathedral Square was designed by William Clayton, the Colonial Architect, and built in 1877-1879 at a cost of £14,521.17.3. Tasmanian-born Clayton had trained in England and worked in Tasmania before arriving in New Zealand. Clayton died soon after the foundation stone for the Chief Post Office was laid and his senior assistant, P.F.M Burrows, carried out the supervision of the building of the Post Office. Burrows, who replaced Clayton but never received the title of Colonial Architect, also designed the later addition to the westward end of the northern façade in 1907. The Christchurch Chief Post Office was built in an Italianate style combining classical and Venetian Gothic elements, such as the pointed arches over the upper windows. Peter Richardson has argued, in his thesis on government architecture in New Zealand, that both the Lyttelton Government Buildings, and the Christchurch Chief Post Office recall Clayton's earlier Italianate design for the Government Buildings in Wellington. These two later buildings differ in the materials used (brick instead of timber), and in the use of Venetian Gothic elements on the facades, a stylistic preference which Clayton saw as particularly appropriate to Canterbury. On the east façade is a clock tower with the British coat of arms above the main entrance. Initially the building housed Immigration, Customs, and Public Works as well as the Post Office. In 1881 the first telephone exchange in New Zealand was installed in the building, where it remained until 1929. (After that date the telephone exchange was housed in Hereford Street.) In 1907 the building was extended by the addition of a third gabled bay to the western end of the north frontage. From 1913, when the Government Buildings on the other side of Cathedral Square opened, the Post Office was the main occupant of the Chief Post Office, although the Tourist Department retained a bureau there until the 1950s. The Chief Post Office had been threatened with demolition since the 1930s when the need for a new Post Office was first mooted. However it was not until 1989 that construction started on a new seven storey building, which was erected behind the original north and east wings to provide Telecom with a new telecommunications centre. Some of the original building was demolished during this process. The Chief Post Office has been a notable feature of Cathedral Square since its completion and provides an important nineteenth century element among the varied buildings around the Square. It is historically significant as one of the early major post offices in New Zealand and as the home of the first telephone exchange in New Zealand.