The city wall is a major feature of the ancient city of Xi 'an. Even now, we call the place inside the city wall "into the city", although
The city wall is a major feature of the ancient city of Xi 'an. Even now, we call the place inside the city wall "into the city", although this city is no longer the core business and economic place of Xi 'an. In retrospect, East Street was a must-visit place for college students every weekend, and the outside of East Gate was desolate. Just because of a wall, it seems that there are two eras. Walking around the city wall, I found that except the corner of the southwest city is round, the other three corners are square. According to our conventional understanding, it is reasonable to make the corners of cities square, so why are the corners of southwest cities round?
There is the following statement:
Today's Xi 'an City Wall was rebuilt on the basis of Chang 'an Imperial City in Sui and Tang Dynasties from the third year of Hongwu (1370) to the eighth year of Hongwu (1375). The city corner is a solid platform protruding from the wall at the corner of the city wall, and the building above is the turret. The role of the city wall is to resist the invasion of foreign enemies. It is easy to observe the movements of the enemy at the height of the turret and facilitate concealment. The southwest corner of the circle is the ruins of the corner platform of Han Jianxiu's "New Town" in the Tang Dynasty. When the Ming Dynasty was repairing the walls of the Tang Dynasty, Zhu Yuanzhang 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.
One theory holds that the traditional architecture in China is greatly influenced by the requirements of gossip and geomantic omen, and the architecture should not be too symmetrical. If it is too symmetrical, it will affect the health and wealth of residents, so the vertical central axis of the front and rear doors of residential buildings must be staggered by a certain distance. For example, there are four streets in Xi 'an, between South Street and North Street, and between East Street and West Street.
In other words, geologists recently found a crack outside the southwest corner of Xi 'an city wall when they were studying the landform of Xi 'an, which passed through in a state parallel to the city wall. If the southwest corner is square, it will affect the firmness of the whole city wall. So we must locally modify the square to avoid cracks and build it into a circle.