The layout wisdom of the Forbidden City-facing the mountains and facing the water, taking the positive center.

　　The layout of the Forbidden City embodies the designers’ wisdom. The clever thinking of "facing the mountain and facing the water" is one of the obvious characteristics. Jingshan Mountain is in the north of the Forbidden City, and Neijinshui River is in the south. There were no mountains in Beijing. When the Forbidden City was built in Yongle period, more than 1 million cubic meters of soil was excavated by opening a moat, and the piles of muck demolished by the Yuan Dynasty Palace could not be treated. So, a "waste utilization" came, which piled up the soil into mountains and planted trees on them. This is the Zhenshan in the north of the Forbidden City. Zhenshan was called "jingshan park" in the Ming Dynasty, and it was renamed "Jingshan" in the Qing Dynasty, and it has been used ever since. Jingshan is the commanding height in Beijing, which is east-west and narrow in the north-south direction, much like a screen. At the same time, when the Forbidden City was built, a culvert was dug downstairs from the northwest corner to introduce the moat water into the city. This is the specially dug Jinshui River. Jinshui River winds south through Chenglong Temple, winding all the way, turning east through Wuying Hall, passing Taihe Gate and Wenyuan Pavilion, and flowing out of the Forbidden City from the southeast corner. Jinshui River not only provides drainage channels for people in the Forbidden City, but also echoes with Jingshan Mountain, forming an aesthetic image of mountains, rivers and mountains in harmony. The surface of Jinshui River is lower than the ground of the Forbidden City, and the main part of the Forbidden City is built on the balcony between Jingshan and Jinshui River. Through Jingshan Mountain and Jinshui River, the Forbidden City is in harmony with nature in the aesthetic sense.

　　"negative yin embraces yang" is also a feature of the layout of the forbidden city. All the important palaces in the city face south. Chapter 42 of Laozi’s Tao Te Ching says: "Everything is negative and holds Yang, and rushing into the air is thought to be harmonious". It means that everything in the world is shady and sunny, and yin and yang interact to form a new harmonious body. The important palace buildings in the Forbidden City face south, with a large number of doors and windows in the south and fewer doors and windows in the north. The Book of Changes, Zhuan Zhuan Zhuan, says, "Sages listen to the world from the south, and govern from the Ming Dynasty", which means that the ancient sages ruled the world by listening to the south and facing the bright sunshine. Similarly, this layout has scientific significance in geography: the Yellow River Basin in China is located in the most remarkable subtropical monsoon climate area in the northern hemisphere, and in winter, a high pressure is formed in the northwest of the Asian continent, with a northerly wind for several months; In summer, the center of high pressure turns to the southeast Pacific Ocean, and the rainy monsoon from the south makes the temperature rise and the summer heat pressing. Under this geographical condition, it is most suitable for the building to face south, with the north side closed to keep out the cold, and the south side with windows for sunlight and ventilation in summer.

　　Another feature of the layout of the Forbidden City is "taking the positive center". "Correcting" means that the north-south direction is the main axial direction of the building layout. This is mainly due to the construction experience of ancient Chinese craftsmen based on the geographical location and natural environment of China, that is, the main seat faces south and is symmetrical left and right. "Centripetal" means that all secondary buildings face the main building. All the ancient buildings in the Forbidden City are mainly quadrangles, with the main rooms facing south and the wing rooms facing east and west. This centripetal architectural style not only makes the distance between houses smaller, which is conducive to the convenience of transportation, but also reflects the idea of "China is supreme" and "China is still big" in ancient China culture. At the same time, this orientation layout reflects the unity and coordination of the ancient buildings in the Forbidden City, and there is no sense of clutter.

　　The architectural division of the Forbidden City is also particular. From the perspective of architectural functional zoning, the layout of the Forbidden City includes the imperial court area and the imperial court area. The buildings of the former dynasty were located in the south of the Forbidden City, mainly including the Hall of Supreme Harmony, the Hall of Zhonghe and the Hall of Baohe (commonly known as the Three Great Halls), which was the place where the emperor held important ceremonies. The imperial palace buildings are mainly located in the northern part of the Forbidden City, including Ganqing Palace, Jiaotai Palace, Kunning Palace (commonly known as the last three palaces) and the East and West Six palaces, which are the places where emperors and empresses live. The three great halls of the former dynasty occupied a large area and formed a huge pattern in the Forbidden City. These three buildings stand on a three-story platform, which is 8.13 meters high and takes the form of Sumitomo. Sumeru is actually the base of the Buddha statue. "Sumeru" is an Indian Buddhist term, which means "the center of the universe". Sumeru is used as the foundation of the building, which means that the building is stable and long-lasting. The three-story platform of the three halls can highlight the grandeur and height of the building, form an obvious contrast with other buildings in the Forbidden City, and highlight its extraordinary position. Not only that, the three halls are elegant in richness and dignified in exquisiteness, which highlights the majesty of the emperor. The Three Great Halls are not only the center of the Forbidden City, but also the center of Beijing, with the axis from Yongdingmen in the south to the Bell Tower in the north, becoming a straight central line. On both sides of this axis, buildings with less important functions are arranged symmetrically and orderly in turn. There is also a square with an area of 30,000 square meters in front of the Hall of Supreme Harmony. This layout is conducive to showing a grand scene when holding important ceremonies.For the six palaces of the East and West, they are symmetrically arranged and vertically arranged. These buildings are separated vertically and horizontally by the East-West Second Long Street and the alleys in front of the palace, forming a very regular and rigorous closed space with streets and lanes, and the doors and walls of the seats are connected and separated. In their own space, that is, in the independent courtyards of each palace, they have the same layout and basically the same architectural form. The plane of each palace is square, and the layout is in the form of a three-in-one courtyard with two courtyards. The front hall and the back bedroom are all equipped with halls, which are strictly symmetrical. The layout of the courtyards of the East-West Six Palaces is subtle and compact, which not only guarantees the privacy of the life of the Empress Dowager, but also has reasonable planning: "How deep the courtyards are" can reflect the location characteristics of the East-West Six Palaces in the Forbidden City. On the whole, the architecture of the former dynasty was Yang, and Yang was majestic and tall. The architecture of the imperial palace is yin, and yin converges to the reality of hiding. The six palaces in the east and west and the three halls form a harmonious and unified wisdom thought of rigidity and softness, yang and yin.

　　In addition, the architectural layout of the Forbidden City was convex in the former dynasty and concave in the imperial palace. The combination of convex and concave is just like a mortise and tenon. This layout of tenon-mortise connection not only shows the ingenious tenon-mortise locking concept of the ancient buildings in the Forbidden City, but also embodies the concept of "Yin and Yang in one" in ancient Chinese architectural culture, which is a reflection of the wisdom of the builders of ancient architecture.

　　(The author is a research librarian of the Palace Museum)