Look at the city wall again. Why is there a corner missing in the southwest of the city wall?
This deviated from China's ancient thought that the sky was round. According to China literature, the theory of "covering the sky" has been widely circulated. Some people think that the jade cong, a representative artifact in Liangzhu culture period, is a symbol of the theory of "covering the sky" and its shape is "the sky is round" It is an annotation of "the unity of heaven and man". China's traditional culture advocates "harmony between man and nature" and pays attention to learning from nature, which is a special annotation to this world view.
According to textual research, the existing old wall of Beijing was built in the Yuan Dynasty and shaped in the Ming Dynasty. 12 15, Mongolian troops occupied Zhongdu city and burned Miyagi, but Daning Palace in the suburbs was spared. From Kublai Khan to the fourth year of Yuan Dynasty (AD 1267), Yuan Shizu built a large-scale new city-Dadu with Daning Palace as the center. This huge project took four years. The establishment of the capital in Yuan Dynasty opened a new chapter in the history of urban architecture in China.
In the design of the whole city, it embodies the traditional principle of building a capital in China, that is, "the former dynasty has a market outlook, and the left ancestor has a right society." Yuandu Miyagi is located on the east bank of Taiye Pool (now Beihai and Zhonghai). The center of Miyagi lies on the central axis of the city. Long Fu Palace and Sheng Xing Palace are built on the west bank of Taiye Pool. Three groups of palaces were surrounded by city walls, which later became imperial cities. The whole imperial city constituted a "former dynasty". Behind the imperial city (now the bell tower and drum tower are the rules), The Book of Rites says, "Set up a city and don't bully Fiona Fang. Zhu Yuanzhang's revised tender pool schema shows the world, which also leads to the fact that most cities built in the Ming Dynasty follow this formula, that is, four corners are missing one corner. In this way, the four walls of Beijing are not rectangular, and its northeast corner, southeast corner and southwest corner are neat right angles, while the northwest corner from Deshengmen to Xizhimen becomes a corner.
Some historians and archaeologists believe that the northern wall of the capital of the Yuan Dynasty is five miles north of Deshengmen and Andingmen, and the remains are still there. It is worth noting that its northwest corner is a right angle. When Beijing was rebuilt in the Ming Dynasty, in order to facilitate defense, the North City was abandoned and a new wall was built five miles south of the original wall. The western section of the newly-built North City Wall passes through the narrowest part of the Jishuitan at that time, and then turns to the southwest, separating the western end of the Jishuitan from the city, so the northwest corner becomes an oblique angle. In the early Ming Dynasty, the water in Jishuitan was much deeper and the area was much larger than it is now. For the needs of city defense and architecture, it is reasonable to chamfer the city wall according to the terrain. Therefore, this view is accepted by most people.
In recent years, some geologists have put forward different views. When they studied the satellite photos, they found that there happened to be a fault parallel to the city wall, which they called Chegongzhuang, namely Deshengmen fault. But on the outer side of the corner wiper, a right-angled image can be faintly seen in the satellite photo, which may be the image of the old wall base opposite. So, some geologists put forward such an idea; When the northwest corner of the city wall was first built, it was probably built at a right angle, so the northwest corner of the city wall was just diagonally broken. Because the foundation is located in the fracture zone, there is likely to be some weak activity at the fracture zone, which affects the firmness of the city wall. Perhaps it was because it collapsed many times that it was rebuilt into this corner wall. In this way, the wall also cleverly avoids breaking, and then it can last forever.
Because there are no exact records in ancient books and history books, people can't determine which statement is the historical truth. To find the answers to all the questions, there is no doubt that scholars need to do further exploration, analysis and research.