Yancheng Site, about 2700 years old, is the most completely preserved ancient ground city site in the Spring and Autumn period. With its long history, unique shape, precious cultural relics and original ecological environment, it has attracted the attention and interest of scholars of insight at home and abroad. It has been called “the military fortress of Wu-Chu struggle for hegemony, the specimens of city defense in the cold weapon age”, and “the first water city in China” by archaeologists and travelers.