Cathedral is the name given to the most important church in a diocese. Emmanuel Cathedral is built out of clay brick, a material indigenous to the alluvial plane of Durban. It is built in the Gothic style and noted for its basilican plan and section. The interior is multi-coloured, with the arcade clad in marble, the clerestory of brick, and ribbed vaults distinguishing the aisles and nave. The corner tower, which is square on plan, was changed to become octagonal, replete with turret, belvedere, lantern and spire.