Beijing, the ancient capital that has gone through thousands of years of ups and downs and vicissitudes, carries the precipitation of Chinese history and culture. From the "Yuan Dadu" of the Yuan Dynasty to the Beijing of the Ming and Qing dynasties, Beijing's urban layout has been constantly evolving, but it has always maintained a unique structure and cultural heritage. Today, let's take a closer look at the four-fold structure of Beijing, which is not only a magnificent display of construction engineering, but also the crystallization of the wisdom of ancient urban defense and governance.

As the capital of the unified feudal dynasties of the Yuan, Ming and Qing dynasties, Beijing's historical heritage is self-evident. From the world-famous Forbidden City to the mighty Great Wall, from the ancient hutongs to the magnificent Tiananmen Square, every brick and tile embodies Beijing's profound history and culture. As a "famous historical and cultural city", the layout of Beijing also shows the unique concept of ancient China in building a capital and governing the country with its four-fold city design.

The four walls of the palace city, the imperial city, the inner city and the outer city are not only physical defense lines, but also deeply rooted in the spiritual core of ancient Chinese ritual culture. Through this layered distribution of cities, Beijing not only maintains the sanctity of imperial power, but also skillfully divides different social classes and functional areas. Perhaps, this is one of the secrets of Beijing's long-term prosperity.

Back in ancient times, cities were built not just to live, but to preserve. According to the records of "Wu Yue Chunqiu", the purpose of building a city in ancient times was to "build a city to defend the monarch, and build a country to guard the people", which means that the city should not only serve as the residence of the monarch, but also provide security for the people. This idea profoundly influenced the planning of ancient Chinese capitals.

Since the Western Zhou Dynasty, almost all the capitals of dynasties have followed the "chengguo" system, the so-called "inner city is the city, and the outer city is Guo", which makes the functional areas and defensive functions of the city clearly distinguished. Over time, the area of the palace where the monarch was located gradually became known as "Miyagi", and the defense line around Miyagi gradually expanded into "Imperial City" and "Capital City".

Among them, Miyagi is not only the residence of the monarch, but also represents the center of power of the entire dynasty and even the symbol of the empire. The imperial city served more of a dividing role, demarcating the boundaries between the royal family and the common people, and even officials and other citizens were not allowed to enter at will. The capital, on the other hand, was a vast defensive system that surrounded the palace and the imperial city, protecting the core of the entire country.

The establishment of the Yuan Dynasty laid the foundation for Beijing's urban pattern. In 1267, Kublai Khan, the ancestor of the Yuan dynasty, ordered the construction of a new capital in Yanjing (present-day Beijing), and chose the Taiye Pool in the northeastern suburbs of Jinzhongdu as the core. The planning of the new capital was inspired by the Zhou Li Kao Gong Ji, according to which the plan of the new capital was divided into three cities: the palace city, the imperial city, and the capital city. This layout provides a framework for Beijing's subsequent development.

Although the Yuan capital has only existed for more than a hundred years in history, its prosperity is unprecedented. In "The Travels of Marco Polo", Yuan Dadu is praised as "unparalleled", and even adjectives such as beauty and delicacy cannot fully describe its momentum. Yuan Dadu was not only one of the most prosperous cities in the world at that time, but its architectural style and urban structure directly influenced the later Ming and Qing capitals. It is worth mentioning that the earliest form of courtyard houses here also began to sprout in the Yuan capital.

In the Ming Dynasty, especially after Zhu Di moved the capital to Beijing, the structure of the city of Beijing underwent major adjustments. Although inheriting the overall plan of the Yuan capital, Zhu Di optimized the north-south layout of the city, shortening the distance between the north and south cities, especially pushing the north city wall to the south by 2 li, while the south city wall was pushed south by 0 li, and the east and west city walls remained unchanged.

More importantly, Zhu Di demolished the palace city of the Yuan Dynasty and built the Forbidden City on its old site. As the imperial palace of the Ming and Qing dynasties, the Forbidden City became the core of Beijing and marked the further improvement of Beijing's urban layout. At this time, Beijing's urban structure was still a triple city, with the palace city (Forbidden City) located in the most central area, surrounded by the imperial city, and the outer city forming a huge defensive line.

Although Zhu Di, the emperor of the Ming Dynasty, had made bold adjustments to Beijing's urban planning, the city of Beijing in the Ming Dynasty did not reach the four-fold city structure we know today. It was not until the Jiajing period of Ming Shizong that the construction of the outer city really began. In response to the Mongol threat from the north, Emperor Jiajing decided to incorporate altars and other facilities on the outskirts of Beijing into the outer city's defenses to protect important royal rituals from external threats.

However, Emperor Jiajing's ambitions ultimately failed to materialize. His out-of-town work could not be continued due to financial problems, and in the end only the southern part of the out-of-town was completed. As a result, the outer city of Beijing could only be temporarily connected to the existing city walls, forming an incomplete four-fold city structure. Although Emperor Jiajing's project became the largest "unfinished project" in history, it also left a profound impact on later urban planning.

From Beijing's quadruple city to today's urban appearance, what we can see is the interweaving of ancient wisdom and modernity. Perhaps, it is this unique historical and cultural gene that has made Beijing a world-famous historical and cultural city, and also provides endless thinking and inspiration for every one of us living in this city.