Introduction to "Pingjiang Map": "Pingjiang Map" is 2.84 meters long, 1.46 meters wide and 30 centimeters thick. It is a map of Suzhou City in the Song Dynasty (Suzhou was called Pingjiang in the Song Dynasty). It is the oldest stone city plan in the world. It was carved in 1229 and was carved by Lu Gang, Zhang Yundi and Zhang Yuncheng. It mapped the urban structure and architectural facilities of Suzhou at that time. The stele records that there were 359 bridges in Suzhou City, surrounded by moats outside the city, and criss-crossed by rivers in the city, including 6 main north-south rivers and 14 east-west rivers in the city, reflecting The Jiangnan characteristics of "small bridges and flowing water" and "water town Zeguo". There are also 12 ancient pagodas, 65 cross-street archways, more than 50 temples and other places of interest. This stele is an important physical historical material for the study of ancient urban architecture.