To the east of General Tower, because of the narrow ground and steep mountain, it is impossible to build a high and wide city wall. In light of local conditions, this special Great Wall was built with blue bricks on the back of the ridge, which people used to call "barrier wall". This barrier wall, with densely-distributed arrow eyes, various forms, beautiful shape, is very intriguing. It is commanding and facing the trough, enabling you to keep alert when advancing and attacking, retreating and defending. The barrier wall on the small ladder can be described as the peak. Within a vertical drop of more than 20 meters, archery can be made from the arrow hole of the top barrier wall, and the arrow can reach the lowest barrier wall through all the arrow holes of the barrier wall, which is extremely amazing. The defense system which makes advancing and retreating freely possible put people back in the ancient battlefield, and they can't help but want to take a few shooting actions from the arrow hole to appreciate the frontier fortress life. This ingenious architectural style is extremely rare in the Great Wall.