St. Mary's Cathedral, Sydney CBD
St. Mary's Cathedral is the largest church in Australia, and lies in the heart of the Sydney CBD adjacent to Hyde Park. I'm standing along College Street at the edge of Hyde Park (33°52′19.50″S, 151°12′45.80″E) (Google Maps), looking northeast toward the Cathedral.
St. Mary's is famous for its indescribably intricate mosaic marble floor in the crypt, including the scenes of The Creation, so please don't miss it.