Complex sentence: The new city was laid out in a grid pattern centred on Cathedral Square; during the 19th and early 20th centuries, there were few barriers to the growth of the urban area, except for the Pacific to the east and the Port Hills to the south.
Split into simpler sentences: The new city was laid out in a grid pattern centred on Cathedral Square. During the 19th and early 20th centuries, there were few barriers to the growth of the urban area, except for the Pacific to the east and the Port Hills to the south.