Like all other Chinese cities, Suzhou in the 13 century was entirely surrounded by walls and these were the first rebuilding works to be begun. The tablet depicts the walls by means of elevational images and shows clearly the position of the entrance gates. Originally, there were eight gates, but during the Sung period this was reduced to five. Throughout the city, a double system of water and road transportation prevailed and, although for the most part the street system paralleled the canals, the principal generator of the plan was undoubtedly the vascular system. The 1229 plan of the city shows that the total length of the canals was 82 kilometers—78 percent of the total length of the city streets. Within the walls, six canals ran from north to south and fourteen from west to east with many branch canals forming part of the network.
In creating this extensive canal system, the implications for hydraulic engineering design were very considerable. The ancient map of the city shows that the principal routes of the canal system must have been laid down at the beginning of city rebuilding and it is therefore most probable that, for the system of water transportation and hydraulics to have functioned properly, the whole network was built at one time. In which case, this was a huge engineering project calling not only for skill in its execution but for an unprecedented expertise in planning, dimensioning, and programming of the work.