INTRODUCTION
Beijing is the capital of China, “Bei” in Chinese means north and “Jing” means the capital. However, Beijing is not the only capital in Chinese history. “Nanjing”, meaning the capital of the South, is also an extremely important city in Chinese history. As the ancient capital of “Six Dynasties”, Nanjing has a rich cultural heritage and is not inferior to Beijing. Today, Nanjing, as the capital of Jiangsu Province and the top ten cities in China’s comprehensive cities, still plays an important role. Today, with the continuous advancement of urban development, the overall urban structure of Nanjing has changed. However, part of the old city during the Ming Dynasty was still retained, and the overall planning of the city during the Ming Dynasty did not change much. This is mainly due to the city walls of Nanjing. Every ancient city must have walls. And the city wall of Nanjing, because of its length, degree of protection and cultural significance, has been regarded as a cultural treasure of Nanjing to this day. Every ancient city must have walls. And the city wall of Nanjing, because of its length, degree of protection and cultural significance, has been regarded as a cultural treasure of Nanjing to this day.
The article will be divided into four sections. First, I will introduce the urban planning of the capital city, Nanjing, in the Ming Dynasty. At the same time, I will compare the northern capital, Beijing, to show the completely different urban patterns and the traditional Chinese culture contained in Nanjing City. Second, I will introduce the Nanjing City Wall, and explain the special features of the Nanjing City Wall from the aspects of architectural style and cultural significance. Third, based on the historical context, from the Ming Dynasty to modern times, I will introduce how the city walls of Nanjing changed according to the needs of urban planning in different periods. Finally, I will introduce the city planning of Nanjing and the protection of the ancient city walls.
URBAN PLANNING FOR THE CAPITAL OF MING DYNASTY
As a capital city that was built in the southern part of China, Nanjing’s urban construction has strong characteristics. Historically, the ancient Chinese city walls were mostly rectangular, while the shape of Nanjing city walls was very complicated. The Nanjing City Wall is surrounded by the tortuous terrain along the perimeter of the palace, the commercial area, and the military area. Its general plane is narrow in the northwest, wide in the east and west, and has a palace fan shape.(Zhang 1985) In addition to the constraints of politics, economy, military, culture, and geography at the time, the design ideas of the ancient Chinese capitals will also draw lessons from “Fengshui”. The construction of the city, the layout of the houses, and the planning of each area would be modeled by the astrology. The specific location of each house on the ground would be determined according to the position of the stars in the sky as well. The Yuan Dynasty, the dynasty before the Ming Dynasty, was a Mongol dynasty. It was natural to rely on the Han nationality’s own culture to consolidate its rule when the Han ethnic people wanted to restore the country. The success of the founding emperor Zhu Yuanzhang of the Ming Dynasty was also attributed to the support of traditional Chinese religious groups, Taoism. Zhu Yuanzhang himself is also a believer in Taoism. Through a series of religious propaganda, people are convinced that he is the Heavenly Son chosen by Heaven. Therefore, when choosing the capital of the new dynasty and constructing it, Zhu Yuanzhang still adopted the guiding ideology of Taoism. To reflect Zhu Yuanzhang’s “dominance of imperial power”, when designing the city walls of Nanjing, the design idea was mainly to imitate the projection of the cosmic celestial phenomena. Based on the historical background at that time, the special geographical conditions of Nanjing, the old city walls of Nanjing and the needs of military defense, they designed the city of Nanjing as a “North Dipper” and “South Dipper”. A division is made from “the Gate of Accommodation”(Tongji Gate, 通济门) in the southeast corner of the city wall to “the Gate of Frozen Mountain”(Zhongfu Gate, 钟阜门) and “the Gate of Phenix”(Yifeng Gate, 仪凤门) in the northwest corner, with “South Dipper Six Stars” in the south and “North Dipper Seven Stars” in the north. These 13 stars correspond to the 13 gates of the Nanjing City Wall. Because “north dipper” symbolizes imperial power, and “south dipper” symbolizes the people, it is a metaphor for the “Ming Dynasty” created by “civilian emperor” Zhu Yuanzhang, and the emperor will live equally with common people and built bright future.

Old Nanjing City
It is not difficult to find the difference between Nanjing and Beijing. Beijing’s terrain is flat, the city is square, the palace is located on the central axis of the city, and it has the meaning of centralization. Nanjing City was built beside mountains and rivers, reflecting an idea of adapting to nature. At the same time, the Royal Palace is located inside the spoon of the “North Dipper”, which means the prosperity of the country. We can see from the city walls of Nanjing and the construction of Nanjing that traditional cultural thoughts play an important role in Chinese architecture and urban planning. But traditional cultural ideas are rich, and different cities have different ideas to support them.(Yang 1999)

Nanjing City’s Gates and two “dippers”
INTRODUCTION OF THE NANJING CITY WALL
Construction of the Nanjing City Wall began in 1366 and was completed in 1393. According to the Royal Archives, the length of the city wall is equivalent to this system, which is about 33.383 kilometers. Nanjing city wall has three major characteristics. First of all, as mentioned above, the city walls of Nanjing are not square but are constructed into irregular polygons according to the geographical conditions of Nanjing. Second, most of the city bricks of the Nanjing City Wall are engraved with words, which record the information of the place where the brick was produced, the person responsible and so on. This is rare in the construction of city walls. The third point is the construction method of the Nanjing city wall adapted to local conditions. Next, I will proceed with these three characteristics to further explain the important value of Nanjing City Wall.

The text on the brick
The cause of irregular polygons in the construction of the city walls of Nanjing is not only due to Chinese traditional thinking but also related to the geographical conditions of Nanjing. In southern China, the climate is mild and rainy, and the rivers are densely networked. The Yangtze River Delta where Nanjing is located in an alluvial plain and the soil is softer than that of northern China. Besides, Nanjing is located along the Yangtze River in the north and lakes and mountains in the east. If the traditional square city planning model is adopted, these natural elements will be incorporated into the urban area, and the construction of the city wall will be more difficult. Also, the terrain of Nanjing is not flat. If a square city structure is adopted, the internal terrain of the city will vary, which is not conducive to urban construction needs such as water supply and drainage. Therefore, after integrating various factors, the city builders are ready to build the walls according to the natural conditions. At the same time, the emperor found an explanation of traditional Chinese culture for this irregular urban pattern. With the blessing of metaphysics, people are also willing to trust the new government.
The text on the brick has the following importance. First of all, it embodies the responsibility system during the construction of the city wall. Since the construction of the city wall is a very important project, to prevent the problem of the city wall during or after the construction, and to quickly find the responsible person after the problem, the builders required that each brick be engraved with information. Secondly, modern people can find the source of the brick from the information. For example, the information collected now shows that the bricks needed to build the city walls come from five different provinces. From this point, we can see that the cost of building the city walls in the Ming Dynasty at that time, as well as the situation of industrial development at that time, and so on. The third point is that the simplified process of Chinese characters can be found in the information of the bricks, which is the cultural significance of the Nanjing City Wall. After the city wall is built, there will always be some unavoidable damage, so brick factories in specific areas are required to produce bricks. Bricks from different periods can be seen in the same area, and the text information of these bricks is also very different. The most important piece of information is the evolution of Chinese characters. For example, the character “Wan” (ten thousand) has been reduced from the earliest “萬” to the “万” which we are still in use today.
The height of the Nanjing City Wall is the highest in the entire Chinese city wall, ranging from 12 meters to 24 meters. Depending on the terrain and geology, different materials and masonry methods are used. For example, giant strips of stone are used to build each piece of about 2,000 kg, in some areas, the entire section of wood is used to piling to solidify the foundation, and in some areas, the mountains are even covered with walls. The adhesives used in the construction of the Nanjing City Wall, the design of the gates, the use of terrain, water supply, and drainage facilities, and the reinforcement of the foundation all condense the wisdom of the ancient people. In a sense, the Nanjing City Wall is a multi-disciplinary historical work involving archaeology, architecture, mechanics, thermals, chemistry, and so on.
NANJING CITY WALL’S ADAPTATION TO URBAN PLANNING
After the capital was moved to Beijing in the Ming Dynasty, Nanjing’s status began to decline, and the protection of the city walls of Nanjing was gradually ignored. After the fall of the Ming Dynasty, the Manchu dynasty, the Qing Dynasty, also established the capital in Beijing. Nanjing, as a city of traditional Han culture, has worsened its decline. During this period, the urban planning of Nanjing City did not change much. In the period of the Republic of China, because the ancient city of Nanjing no longer met the needs of the city planning of the capital at that time, the government of the Republic of China decided to take measures to demolish some of the city walls, open new city gates and rename the city gates. In the tenth year of the Republic of China (1921), to prosper business activities on the banks of the Yangtze River, with the support of Han Jun, the then Chief of the Civil Affairs Department of Jiangsu Province, he broke the wall on the southwestern wall of the Gate of Phenix and built a road from the gate to the riverside pier and fills up part of the river. At the same time, a new gate named “the Gate of Sea Hill”(Hailing Gate,海陵门, now “the Gate of River Control”, Yijiang Gate, 挹江门) was opened, which shortened the distance from the river to the city.
In July of the 17th year of the Republic of China (1928), the National Government ordered to change the name of the city gate of Nanjing to rectify the atmosphere of the capital. The Toward Sun Gate(Chaoyang Gate, 朝阳门) became the Zhongshan Gate (中山门, in memory of Mr. Sun Yat-sen ’s achievements), the Gate of Phenix became the Xingzhong Gate (兴中门, “Xingzhong” means rejuvenate China) and the Gate of God Will (Shence Gate, 神策门) became the Heping Gate (和平门, Heping means peace), etc. In the same year, the National Government rebuilt the single-hole Zhongshan Gate into three-hole.
In the period of the People’s Republic of China, the Nanjing City Wall experienced another wave of change. Around the 1950s and 1960s, the demolition movement that swept across the country spread to Nanjing. Like the ancient city walls in other cities, the restoration and protection work once took a tortuous course. Due to historical limitations and the influence of the “left” ideological trend, the Nanjing city wall had been in danger of being completely demolished on several occasions. Fortunately, Mr. Zhu Xie, deputy director of the Jiangsu Provincial Culture Bureau, immediately made an urgent proposal to the leaders of Nanjing and ordered the suspension. At the same time, a report was sent to the Central Ministry of Culture, calling for the protection of the Ming City Wall. With the repeated efforts of Mr. Zhu Xie and others, some citizens also wrote to the municipal government of Nanjing, which ultimately allowed the Nanjing City Wall to survive. In 1954, to facilitate transportation inside and outside the city, the Nanjing Municipal Government decided to open a new door on the Nanjing city wall. However, to comply with the urban planning of Nanjing at that time, the Nanjing Municipal Government also adopted the decision to open a new gate, the “Gate of Revolution”(Jiefang Gate, 解放门) is one of it. Also, this name has a very Communist color. The Nanjing City Wall has undergone a series of events including demolition, rename of the gate, and opening of a new gate. It is like a living history book, which records the changes in Chinese culture from the Ming Dynasty to modern times, and the aesthetic taste of Chinese people in different periods.

Nowadays Zhongshan Gate, with three holes
THE PROTECTION OF NANJING CITY WALL
The city wall has very important historical significance, and it is not appropriate to dismantle the city wall because it does not conform to today’s urban planning schemes. Most of the ancient city walls in the world have been destroyed, and some have disappeared. Nanjing is a lucky city, and most of the city walls still survive. With the development of China’s economy, the government has gradually shifted its focus to culture after having sufficient economic level support. The most important point is cultural protection. On July 16, 1982, the Nanjing Municipal Government issued the “Notice on the Protection of City Walls”, stating that “Nanjing City Walls are an important cultural heritage of the motherland.” This announcement officially marked the officialization of the protection of the Nanjing City Wall. At the same time, the circular also suggested that every Nanjing citizen should know the city walls and take the initiative to protect them. The “Administrative Measures for the Protection of Nanjing City Walls” was enacted by the Nanjing People’s Congress in 1995 and approved by the Jiangsu People’s Congress in 1996. Since then, the law has protected the city walls of Nanjing.(Lin 2006)
However, there are still some difficulties in protecting the city walls of Nanjing today. First of all, some citizens still do not have the consciousness to actively protect the city walls. In the voice of the masses, some people still think that the city wall will affect the development of Nanjing city, and protecting the city wall is a waste of public resources. Secondly, the Nanjing City Wall involves five administrative districts within the city. The status quo of a complete city wall divided into different areas for management makes it impossible to carry out unified planning for the protection and use resources rationally and effectively. Objectively speaking, the Nanjing Municipal Government has made great efforts to protect the walls of Nanjing. However, the protection of the Nanjing City Wall does not happen overnight. It must take time and effort to continue the protection work.

The Ming City Wall has become a famous scenic spot in Nanjing
CONCLUSION
No matter how the urban planning thinking of Nanjing City changes, it must be inseparable from the ancient city walls. With the establishment of Nanjing City, Nanjing City has now passed for hundreds of years. The Nanjing city wall has lost its role in defending the capital over time. But we can still see a hundred years ago from the existing Nanjing city walls. The city wall also showed his charm in history. Every dynasty wanted the city wall as a witness to record the stories of their era. The city walls contain traditional Chinese culture, recording how the Chinese plan their cities. This is important information for contemporary Chinese research history, and even for foreigners studying China. The city walls of Nanjing are inseparable from the development of the city of Nanjing. He will always remind the Nanjing people where their roots are.
Zijian Zhang
CITIES AND URBANISM IN ASIA PACIFIC_UPF
Bibliography
Lin, Chun. 2006. “On the Protection of Nanjing City Wall.” [论南京城墙的保护] Jiangsu Local History, no. 03: 55–58.
Yang, Guoqing. 1999. “A Probe into the Design Thoughts of Nanjing City Wall in Ming Dynasty.” [明南京城墙设计思想探微] Southeastern Culture, no. 03: 66–71.
Zhang, Quan. 1985. “Nanjing city planning in early Ming Dynasty.” [明初南京城规划] Journal of Nanjing Institute of Technology, no. 03: 113–23.
Pictures from the Internet