Christchurch is one of those cities that lost their cathedral in the earthquake tho I am not sure what is there now.
It was a very famous stone cathedral in the centre of town and much loved.
Auckland does not have anything similar although it does have several very old large churches, the kind with huge steeples, church organs, naves, stained glass windows, etc. I would say the Trinity Cathedral in Parnell is one of them, although it isn't the oldest. If you want to have a fancy church wedding, Aucklanders always book out the one in Parnell, because it's an old wooden Selwyn style church with stained glass windows, wooden pews, and fancy fretwork.