Xian City Wall
At the time when Zhu Yuanzhang captured Huizhou, long be fore the establishment of the Ming Dynasty, he was astonished by a hermit named Zhu Sheng, who told him to "build high walls, store abundant provisions and take your time in proclaiming yourself emperor", advice which Zhu Yuanzhang heeded. Once the whole country was unified, he sent orders to the local governments to build city walls on a large scale. Zhu assumed that "out of all the mountains and rivers in the world, the central Qin is the most strongly fortified and strategically impregnable. The city wall 0[ Xl'an is an extension of the old Tang Dynsty structure, as a reslt of this wall building campaign. Xi'an's city wall after its enlarge-ment in the Ming Dynasty stands 12 metres high. It is 12--14 me-tres across the top, 15--18 metres thick at bottom and 13. 7 kilo-metres in length.
There is a rampart every 120 metres. The ramparts are towers that extended out from the main wall, the top of the rampart being at the same level as the top of the wall. The ramparts were built to allow soldiers to see those enemies who would try to climb the wall. The distance between two ramparts is just within the rage of arrow shot from either side. This allowed soldiers to protect the entire wall without exposing themselves to the enemy. There are altogeth-er 98 of them on the wall; each has a sentry building on top of it. The weapons in ancient times were primitive. The gates of the city wall were the only way to go into and out of town. Therefore, these gates were important, strategic points, that the feudal rulers racked their brains to try to defend. In Xi'an's case, the east, west, south and north gates, each consists of three gate towers. The main gate tower is called Zhenglou. Zhalou is tile gate tower with the suspense bridge, and Jianlou is the arrow tower. The Zhalou tower stands away from the wall. It is used to lift and lower the suspense bridge. The Jianlou tower is in the centre of the oth-ers. Its front and the two outer sides have square windows to shoot arrows from. The Zhenglu tower is the inner one. It is the main en-trance to the city. Jianlu and Zhenglou are connected by tunnels, called Wongcheng in which soldiers could be stationed. From the Wongcheng there are also horse passages leading to the top of the wall. These are gradually ascending steps made so that it is easy for war horses to ascend and descend. There are all together 11 horse passages around the city.A watch tower is located on each of the four corners of the wall. The one at the southwestern corner is round, probably after the model of the imperial city wall of the Tang Dynasty, but the other three are square-shaped. On the top of the watch towers there is a corner rampart, higher and larger than the ordinary ramparts. This shows the strategic importance of the corners of the city wall in war times. Along the outer crest of the city wall there was con-structed crenelations or battlements, from which arrows were shot and watch was kept. The lower, inner walls are called parapets. They have not crenels. They were used on the inside of the wall to prevent soldiers from falling off the wall when travelling back and forth on top of the wall.
The first city wall of Xl'an was built of earth, rammed layer upon layer. The base layer was made of earth, quick lime, and glutinous rice extract, tempered together. It made the wall ex-tremdy strong and firm. Later, the wall was totally enclosed with bricks. On top of the wall, there is a brick water trough every 40 --60 metres, they are used for drainage. They have played a very important role in the long-term protection of the city wall of Xl'an. A moat, wide and deep, runs around the city. Over the moat,, there used to be a huge suspense bridge which would cut off the way in and out of the city, once lifted.Thus, the Ming Dynasty City Wall formed a complex and well-organized system of defense. It is also the most complete city wall to have survived through China's long history. The city wall itself is a true display of the ability and wisdom of the working peo-ple in ancient times. It provides valuable and substantial material f0r the study of the history, military science, and architecture of the Ming Dynasty.