Every surviving and still in use building in a big city or small town has its unique value and significance. For the past, it was a commemoration; For the present, it is life; For the future, it is a legacy. As the capital, Beijing, which keeps up with the times, not only has trendy new buildings and landscapes such as the National Centre for the Performing Arts, Bird's Nest, Water Cube, Ice Ribbon, and Aosen Park, but also carefully preserves grand historical buildings such as the Great Wall, Forbidden City, Summer Palace, Heaven, Earth, Sun, Moon, and Earth Altar, Drum Tower, etc. These buildings and landscapes showcase the endless cultural vitality of ancient China to the world. The hutong lifestyle centered around courtyard houses also has equally important value. A quadrangle courtyard is not just a courtyard with several entrances and exits, a clear layout, and rooms with different functions. Its key point is precisely the ethereal and comfortable "empty space" reflected in the courtyard walls and between walls. It is the beautiful artistic conception expressed by Chinese classical poetry in the use of "empty space" by those who are in it. Inside the courtyard, there is a pomegranate tree symbolizing many children and blessings. Inside and outside the windowsill, colorful goldfish swim leisurely in the glass jar. From April to October every year, there is a summer shade under the ceiling built in the courtyard, with some hanging clusters of grapes or gourds of various sizes, as well as various shapes of birdcages embellished among them. In the book "The Artistic conception of architecture", architect Xiao Mo pointed out that the empty space of Beijing's quadrangle courtyard "is not about people surrounding the building, but about buildings surrounding people", not a static "expectation" but a dynamic "playable". The pattern of being closed to the outside, open to the inside, and enjoying oneself is twofold: on the one hand, self-sufficient families need to maintain some kind of isolation from the outside world to avoid natural and social disasters, and to maintain a peaceful and private life; on the other hand, the mentality of agricultural production makes people "particularly happy to be close to nature, willing to see the sky, earth, flowers, and trees at home at all times". The elegant atmosphere of the quadrangle courtyard is rooted in the industry ecosystem of Beijing in the past. The elegant enjoyment of tea tasting, fish watching, and bird watching has driven the development of tea shops, flower, bird, insect, and fish markets. Listening to and singing songs by the whole family, in a certain sense, gave birth to many intangible cultural heritage of traditional Chinese opera in Beijing today. The courtyard houses that accommodate wealthy families are a form of familial culture. On the contrary, due to various changes, the quadrangle courtyards that have become large courtyards, as well as numerous large courtyards such as those in the Tianqiao area of Nancheng in Beijing, have provided living space for more people and also formed a familiar society. As shown in the TV drama "The Happy Life of Poor Mouth Zhang Damin", the daily living conditions of the large courtyards and small alleys in the old city area, which were later heavily renovated, rebuilt, and demolished, include neighbors looking up but not looking down, arguing over water and building shelters, actively helping neighbors pick up clothes on rainy days, taking care of children, and sharing food with each other. In response to the heritage perspective of time dimension, the old streets of big cities and small towns are not only the aggregation and combination of numerous buildings, but also a collection of scenery, sound, emotion, and charm related to the neighborhood, which is a kind of life posture and way that has existed or is ideal. Whether as a concrete time and space or a strand of emotion, the strong sense of life is closely intertwined with the old street. In the memory of residents, the old street is a place where they start playing and chasing with peace of mind, neighbors help each other, there are constant cries and shouts of goods, and peddlers wander around at fixed times. It remains and manifests in the individual's sensory world. Like homesickness, as the core of "urban sorrow", warmth, slow pace, and human touch are the basic components pointing to the past or ideal old streets. That is to say, the old street is first and foremost a place where people feel a sense of security and happiness when they recall it. For a city with a long history, the space pointed to by the old street and the lifestyle and daily life in that space are not only collective and social facts, but also an ideal life scene and cultural form. Allowing more people to settle down and live in cities has always been the wisdom of ancient China. During the Eastern Jin Dynasty 1700 years ago, the powerful minister Xie An endowed the "Kyoto" with humanism. According to "Shi Shuo Xin Yu: Political Affairs", "During the time of Duke Xie, the soldiers and their attendants died, and many of them fled to Nantang and disembarked in various boats. If they wanted to search for a while, Duke Xie refused and said, 'If this generation is not allowed, how can it be called Kyoto?'" For Xie An, even Kyoto, as a city of space and place, was first to allow people of all kinds to survive. This insight and top-level design are truly a great contribution of Chinese culture to world cities. Let architecture return to its original purpose. A city can only show vitality and vigor if it has heterogeneity, richness, hierarchy, and unevenness. Urban construction, especially the renovation of old cities, should not be demolished and replaced with new ones. Instead, constructive maintenance and upkeep construction should be carried out to ensure that citizens can live in peace and have a poetic dwelling. (Liao Xinshe) (Author Yue Yongyi, professor of the Sociological Theory and Methodology Research Center of Renmin University of China and Beijing Social Construction Research Base)