St Andrew's Cathedral is one of the major Gothic buildings of Sydney and even though small in comparison to many cathedrals is well executed showing the hand of architect Blacket. It is a Gothic Revival cathedral in Sydney freestone of the late Colonial and Early Victorian periods. The exterior has weathered to a mellow warm brown colour which adds to the rich texture created by delicate Gothic windows, well-proportioned towers and buttressing and multiplicity of decorated pinnacles. The main roof is slate.