The third moat in Yancheng from outside to inside is called Imperial City River, which is 500 meters long and 30 meters wide surrounding Imperial City.

Imperial City, also known as Ziluo City, is located in the center of Yancheng Relics Park and is square as a whole. The high wall around Imperial City is called Imperial City Wall, which is built by ramming earth.

It is said that Imperial City was the place where Yanjun ruled the government and lived. Archaeological discoveries of monuments like pillars and caves have proven that there were really large buildings here.