Holy Trinity Cathedral is situated in Parnell, a residential suburb of Auckland, New Zealand.
The first Anglican place of worship in Auckland was Old St Paul's, at the bottom of Princes Street, but Parnell residents tired of walking about 3 km (1.9 mi) over paddocks to reach their church. The first church serving the district was dedicated to St Barnabas. Completed in 1849 it was situated near the bottom of Parnell on land which was later demolished and used for reclamation work. This small church of St Barnabas slowly fell into disuse following completion of Old St Mary's church in 1860, and was eventually shifted to Mount Eden, where it still forms part of the Parish Church. With the building of the original St Mary's Church, Bishop Selwyn established the Parish of St Mary.
Old St Mary's stood near the site of the present cathedral, but proved to be too small, badly ventilated and uncomfortable. The establishment of New Zealand's dioceses, and Auckland's fast growing population, meant that a larger church was required. Old St Mary's Church was demolished and in 1886 work started on land opposite to build a new Cathedral Church of St Mary. This wooden Gothic Revival church was designed by the prominent New Zealand architect Benjamin Mountfort and completed in 1897. The building served as the Cathedral Church and principal Anglican church of Auckland until 1973 when the Chancel of Holy Trinity Cathedral, for which the foundation stone was laid in 1957, came into use. In 1982, St Mary's Church was moved across Parnell Road to its present site beside the Cathedral.
Today the Diocese of Auckland is one of seven dioceses of the Tikanga Pakeha (pakeha culture) stream of the Anglican Church in Aotearoa, New Zealand and Polynesia. The Diocese covers the area stretching from North Cape south to the Waikato River, across the Hauraki Plains and including the Coromandel Peninsula.