The site of Yancheng, with its unique shape and precious cultural relics in 1988, was listed as a key cultural relics protection unit of the State Council. Yancheng is 850 meters long from east to west and 750 meters long from north to south. It is a three-city three-river system. The city walls are divided into triple, all of which are piled up and built with a height of about 3 meters. The city (Wangcheng) is located in the north of the central part of the city, the circumference is 500 meters, near square; the inner city (inner city) is similar to square, the circumference is about 1500 meters; the outer city is irregular circle, the circumference is nearly 2,500 meters.