Traditional urban layout

The main requirements of China's ancient urban construction model are as follows:

(1) City scale. According to the rules of etiquette, the city of the son of heaven is nine miles away, the city of the duke is seven miles away, the city of the marquis and the count is five miles away, and the city of the viscount is three miles away. Among the vassal States, the largest doctor, the capital of Qing Dynasty, should not exceed one-third of the capital, and the smallest one is only one-ninth.

(2) Urban layout. In the history of China, the emergence of a large number of cities should begin in the Spring and Autumn Period at the latest, with palaces as the center, and this layout has been throughout the feudal era. The overall layout of the capital should be a square city with nine sides and ten miles and three doors on all sides. The vertical (north-south) street and the horizontal (east-west) alley cross each other like the warp and weft of cloth, and the width of the street can accommodate nine carriages in parallel. On the central axis and in front of the city (that is, in the south), there is the palace, which "takes justice from the former court" to highlight the dignity of the emperor and flaunt justice. Behind the central axis (that is, the north) is the market trade zone, "the market prospect is for profit." On the left side (east side) of the palace, there is an ancestral hall (now the ancestral hall in Beijing, the predecessor of the Working People's Cultural Palace) dedicated to the ancestors of the emperor. On the right side (west side) of the courtyard, there is a village altar to worship the gods of country (land) and millet (grain). As for residential areas, they are all built into unified alleys and then divided into communities. During the Han and Tang dynasties, residential areas were separated by fences and gates were set on time. Each community is called "Li" or "Fang". For example, in the Tang Dynasty, Chang 'an had 108 square. This is not only conducive to public safety, but also makes the living environment of residents quieter. Until the Song Dynasty, due to the need of commercial trade, the Li Fang system was broken and the fence was abolished. In addition, outside the city wall, it is necessary to dig ditches to fill the moat and plant trees along the river. "Strengthening the city defense will help beautify the environment." This layout makes the whole city a chessboard pattern with a symmetrical axis, which fully meets the needs of feudal rule and facilitates the lives of residents to a certain extent. However, the court is placed in front of the central axis, and the court is absolutely not allowed to pass, so the east-west traffic is blocked.

(3) Building scale. Kao Gong Ji also made clear requirements on the size of the city and the height of the city walls (including the palace walls): "The city faces the same lady" and "The prince has five pheasants". "Biography of the Ram" said: "If the city is pheasant, it will be blocked in the fifth edition, blocked in the fifth, and pheasant in the last hundred years. Sub-note: the city of the son of heaven is a thousand pheasants, seven pheasants high; Everyone is pheasant, and the height is five pheasants; The son is fifty pheasants and the son is three pheasants. " A hundred paces square is a husband, and three feet long and one foot high is a pheasant. Every step

The length of Li varies from time to time, sometimes 6 feet, sometimes 5 feet, but the length of each Li is fixed, which is 1800 feet, that is, when each step is 6 feet, it is 300 steps per Li; When every step is 5 feet, every mile is 360 steps.

(4) Construction steps. There are so-called "seize the day", "land and water in the county (suspended)" and other requirements, that is, unless there are special circumstances, the orientation of the city should be accurate, that is, the central axis should be due south and north, and the ground should be leveled as much as possible to determine the height of buildings such as city walls. Therefore, the emphasis on the correct orientation is not only because of the natural conditions in China, where the main building facing south can be warm in winter and cool in summer, but also because in the traditional consciousness, there is the concept of "facing south as king and facing north as vassal". In order to do this, first erect a long pole and determine the due south direction according to the shadow of the sun. Then, according to the planned location, a ditch was dug at a certain distance outside the city wall, and then water was released in the ditch, and a moat appeared. According to its water surface, you can also get the horizontal plane, and build the city wall with trench soil, which has the effect of killing two birds with one stone.

Of course, the actual situation is much more complicated, and we can't stick to the above regulations and figures, because the natural environment of the city may need proper adjustment and flexibility of the layout. The rise and fall of national strength will also affect the scale of the city. The measurement of each era also has its own size. For example, Chang 'an, the capital of the most prosperous Tang Dynasty in China's history, is very large. The east-west length is 972 1 m, and the north-south length is 865 1 m, covering an area of about 84 square kilometers, which is almost 10 times that of Chang 'an City built in the Ming Dynasty. As the central axis, Zhuque Street is150m wide, with street trees and drainage ditches on both sides. The imperial city and Miyagi are not in the south of the central axis, the imperial city is in the north of the central axis and Miyagi is in the east of the north wall. This is because the terrain in the north of the city is higher, and the construction of the imperial city and Miyagi here can better reflect the dignity of the emperor. Because the whole city (especially the north) looks like the Big Dipper, it is called "the city of fighting". But in general, they are basically built according to the above requirements.

The history of Beijing's city construction began in BC 1045, but it was the Yuan Dynasty that laid the foundation for today's Beijing pattern. In the Yuan Dynasty, the north and south were slightly longer, with three doors in the south, east, west and three sides, leaving only two doors in the north wall and no doors in the north. People think this is to "not vent the emperor's anger", just like Nezha with three heads and six arms. At the beginning of the Ming Dynasty, because the northern city was vulnerable to foreign invasion and contracted inward, the southern city wall moved slightly to the south, so there were only two doors on the east and west walls. But the population gradually increased, so an outer city was built in the south, making Beijing a "convex" shape. The Qing dynasty has remained basically unchanged.