What is the difference between north and south in the layout of ancient cities in China?

The ancient urban buildings in China have created many layout methods adapted to local conditions. Most cities in the north are located in the plain, so the urban plane and road system are mostly square and regular. Cities in the south, surrounded by mountains and rivers, often form irregular layouts because of the combination of topography, but the road system still strives to be neat. In Jiangnan, besides building roads, many rivers have been dug. For example, in Suzhou, at the latest in the 7th century, there were two sets of main rivers and several sluices around the city, and then a set of river network complementary to the streets was excavated in the city, including vertical intersecting trunk lines and branch lines parallel to the streets for traffic and drainage, which fully showed the integrity and rigor of the planning at that time.