Complex sentence: The building is the oldest extant church building in Sydney's inner city region and is listed on the Register of the National Estate and has been described as one of the world's 80 greatest man-made treasures.
Split into simpler sentences: The building is the oldest extant church building in Sydney's inner city region. It is listed on the Register of the National Estate and has been described as one of the world's 80 greatest man-made treasures.