The Xian City Wall is not only the most complete city wall in China, but also one of the largest and most complete ancient military systems of defense in the world. The city walls here were actually built on the fortifications of the Tang Forbidden City. Located in the central part of Xi'an city, the City Wall which built in Ming Dynasty during the period 1374-1378 stands 12 meters high. It is 12- 14 meters across the top, 15-18 meters thick at bottom and 13.7 kilometers in length. It is divided into several important parts like the rampart, the gate tower, the suspend bridge, the watchtower, the moat and so on. The Ming Dynasty City Wall formed a complex and well-organized system of defense. The city wall itself is a true display of the ability and wisdom of the working people in ancient times. It provides invaluable and substantial material for the study of the history, military science, and architecture of the Ming Dynasty.