Xi 'an City Wall is a relatively complete part of the ancient city wall building in China. Its architectural history can be traced back to 1400 years ago, when Daxing City, the capital city, was built in the second year of Emperor Kai of Sui Dynasty (AD 582). On this basis, the capital Chang 'an was built in the Tang Dynasty, which was one of the largest city walls in the world at that time. After five dynasties, song dynasty, Jin dynasty and yuan dynasty, it has maintained the shape laid by sui and Tang dynasties. In the Ming Dynasty, Xi 'an today was established on this basis. The southwest corner is different. The towers at the four corners of Xi 'an city wall are called "turret". If you can walk around the city wall completely, you will find that only the southwest corner of the city wall is round, and the other three corners are square. These city corners with different shapes are actually solid platforms protruding from the wall at the corner of the city wall, that is, the "corner platform", and the building above is the turret. Different shapes of city corners were found in the Ming Dynasty, and the circular southwest corner was the ruins of Han Jianxiu's "New Town" in the Tang Dynasty. In the Ming Dynasty, when Zhu Yuanzhang was repairing the walls of the Tang Dynasty, he ordered the corner platform to be expanded by one third, but the southwest corner was not rebuilt, and the original appearance of the corner platform of the Tang Dynasty was preserved. It is said that the southwest corner is located in the earthquake zone. As long as the corner platform is square, once it is repaired, there will be problems. In the end, there is nothing to do but keep the circle. Another legend is that before the Ming city wall was built, there was an old lady Wang in An, who was tortured by her son and daughter-in-law and eventually starved to death in the street. When local parents knew about it, they asked their son and daughter-in-law near the southwest corner of Xi 'an city wall. Everyone thinks that these two are immoral and unfilial, and the square represents an upright person, so the shape of the turret has not been changed. There is no Xuanwu gate. There are two Xuanwu gates in Xi history. The north gate of Daming Palace is also called Xuanwu Gate, but it is not the Xuanwu Gate of "Xuanwu Gate Change". Xuanwu Gate, the "Change of Xuanwu Gate", is the north gate of Chang 'an Imperial City and the main north gate of Taiji Palace. At the end of the Tang Dynasty, Zhu Wen kidnapped Tang Zhaozong to move eastward to Luoyang. In order to meet the needs of military defense, the Yuguo Army staying in Chang 'an made Han Jianbian abandon Guo Cheng and Miyagi and reduced Chang 'an to the imperial city. Xuanwu Gate was destroyed in the war. According to textual research, its location should be in Huaqiang West Road outside Huancheng North Road today. There are 93 solid platforms protruding from the wall on the horse face of the city wall, which are called enemy platforms, also known as horse faces and wall platforms. The reason why it is called horse face is said to be the wall structure built in the Ming Dynasty. Figuratively speaking, it is an army array composed of 98 horses, and 98 enemy platforms are like upright horses. According to records, there are 98 enemy platforms on the Xi 'an city wall, and only 9 1 was detected in 1982, and 93 enemy platforms have been restored. The distance between enemy platforms is 120m, 15-24m wide, and it protrudes from the city wall by 7m[ Figure 2, 1997- 19 (4-3)]. Setting up enemy platforms and enhancing the defensive ability of the city walls are conducive to guarding the city, so that soldiers can broaden their horizons and use tactics flexibly. There is an enemy tower on the top of the enemy platform, also called the card room and the shop room. During the reign of emperor Qianlong, 90 enemy towers were rebuilt. From 1986 to 1989, Xi 'an rebuilt 12 watchtowers, including 7 south city walls and 5 east city walls, which restored the architectural form of watchtowers on the walls of Ming Dynasty.
Today's Xi 'an City Wall, although far away from the ancient flames of war, is the most intact large-scale city wall in contemporary China and even in the world. It is the crystallization of human wisdom and a miracle in the architectural history of China. As an important historical and cultural heritage, the protection and utilization of Xi 'an City Wall is of great practical significance.
The present Xi 'an City Wall was rebuilt on the basis of Chang 'an City in Tang Dynasty from the third year of Hongwu (1370) to the eighth year of Hongwu (1375).
There is a saying: since Zhu Yuanzhang accepted the suggestion that "building a wall to accumulate grain is king slowly", he deeply felt that "it is not safe to hide in a deep ditch and high base." So counselors Liu Ji and Yao presided over the design of the city to show that the world was built as shown in the picture. After receiving the order, Liu and Yao discussed the revision several times. Finally, Zhu Yuanzhang drew a distance pattern according to the traditional pattern. Unexpectedly, Zhu Yuanzhang said: "Although there are certain rules for building cities since ancient times, according to my experience, you should never stick to the rules. The Book of Rites says, "If you want to make rules, don't bully Fiona Fang". I think it is better to change it. " Then I picked up the brush and erased a corner of the rectangular pattern. Therefore, the urban schema changed by the imperial edict shows that most cities built in the Ming Dynasty are said to follow this formula.
Another way of saying it: When planning the Xi 'an city wall, all four corners were right angles, but later, when dealing with the foundation of the city wall, the ancient Tang Cheng site was accidentally discovered in the southwest corner. In order to save time and effort, the original foundation is used conveniently. This seems reasonable, but archaeologists calculate from the coordinates of buildings such as Little Wild Goose Pagoda and the width of Chang 'an Square street in Tang Dynasty that Xi 'an City has nothing to do with the location of Chang 'an City in Tang Dynasty.
There is also a saying that the traditional architecture in China is influenced by the requirements of gossip and geomantic omen, and the architecture should not be too symmetrical. For example, the front doors of yamen, temples and residential buildings must not be symmetrical with the rear doors, and the vertical central axes of the front and rear doors must be staggered by a certain distance. Another example is the dislocation of four streets in Xi 'an, North Street and South Street, East Street and West Street. As long as you look at the map of Xi city, you can't find this.
It is this "asymmetric" requirement for architecture that determines that one of the four corners of Xi 'an City Wall must not be a right angle. In fact, many examples of "asymmetry" can be found in the ancient buildings of Xi 'an.
In recent years, geologists have put forward a different view: when studying the landform of Xi 'an, they found a ground fissure near the southwest corner of the city wall and passing parallel to the city wall (the recent analysis of satellite photos further confirmed this ground fissure). Based on this, they think that the original design of the city wall was rectangular when it was first built. Because the whole city wall has been fully started, it is impossible to completely modify the drawings, but if the construction continues according to the original plan, it is difficult to ensure its firmness, so they have to make partial modifications to avoid ground fissures and modify it into a semicircle.