Pingcheng, also know as P'ing-ch'eng-chen, is situated in the north of Datong city covered an area from Datong rail station to chenzhuang. It is bordered by Fangshan to the North and the Great Wall to the east. Pingcheng enlarge on the basis of Pingcheng County which was found in Han dynasty. Pengcheng consists of inner city, outside city and outline with an area about 60 kilometers square. There are many earth walls in the Relics of Pingcheng. Some of them are about five meters high, others are about one meters high. The different height of the earth wall shows the range of the imperial palace and feudal official.