Conveniently accessible public spaces are not only an important element of urban quality of life but also part of the real estate value within their service area. From the perspective of land finance drivers, city governments and real estate developers both hope to increase property values. Therefore, the neglect of public spaces is puzzling. One possible explanation is that the provision of public spaces depends on fiscal expenditure, but the costs are difficult to recover. City governments, constrained by land finance, often lend as much commercial and residential land as possible to developers, thereby obtaining more land transfer fees. Developers naturally pursue maximum profits, preferring larger residential sites to build gated communities in large developments and provide more upscale community services than the surrounding environment, thereby creating higher property values and generating greater profits from home sales. Although many gated communities have good shared spaces and children's playgrounds, they are not truly public spaces in the true sense; rather, they are provided as "club products" specifically for gated community residents, while those outside the community are excluded. In the past 20 years, access control communities in high-rise buildings have become a fundamental element of urban spatial development in China and a component of the "thousand cities are uniform." Research shows that gated communities reduce social inclusivity. In addition, gated communities in high-rise developments are actually large blocks that negatively impact the city's street network and traffic, which is one of the causes of traffic congestion.

The profit-driven commercialization of urban construction has led to the loss of public space, which has also appeared in Western city history. Lewis Mumford recorded in Chapter 14 of "A History of Urban Development: Origins, Evolution, and Prospects": "The capitalist economy holds that the laws of urban development mean resolutely and relentlessly clearing out all natural scenery and characteristics in daily life that can elevate human character and provide people with pleasant and pleasant experiences." Rivers can become surging sewage ditches, and waterfront areas can even make it impossible for visitors to approach. To increase driving speed, ancient trees can be cut down, historic buildings can be demolished, but as long as the upper class can drive around Central Park or leisurely ride horses on the horseback trails in London's Hyde Park early in the morning, no one cares about the lack of parks, green spaces, and resting places for the city's residents. It was not until 1870 that society recognized the need for playgrounds for children, but it was too late; land prices had risen, and large sums of money had to be paid to buy land. Thus, the overdeveloped streets in commercial city planning gained a peculiar function: streets were forced to replace the backyards and enclosed small squares of medieval town residences, or the open-air squares and parks of Baroque planning. Thus, the bare paved roads that were originally mainly paved for vehicle traffic have become parks, walking plazas, and playgrounds for children. But it's a dirty park, a dusty walking spot, a dangerous playground. "A disgraceful chapter in the history of Western urban development should serve as a warning for our urban construction and development.

The construction of child-friendly cities is closely related to how China effectively addresses the aging population. With aging and declining birth rates year by year, China's current pension system is becoming unsustainable. The root of the pension problem lies in "raising children," and the rising cost of "raising children" is a major reason for the declining birth rate. The cost of "raising a small child" can be divided into visible costs and hidden costs. Visible costs refer to the expenses and time parents spend raising children, while implicit costs refer to time spent beyond reasonable limits or additional expenses to save on this time (for example, hiring nannies to handle extra time-consuming caregiving work). Broadly speaking, hidden costs also include parents' concerns about their children's safety. Clearly, building a child-friendly city helps reduce the hidden costs of 'raising young children.' In addition, child-friendly cities provide children with a safe and healthy physical environment, which not only helps them grow up healthily but also creates opportunities to enhance children's cognitive and exploratory abilities through beneficial play and cultivate good interpersonal relationships. We must fully recognize all these positive externalities in the planning and construction of child-friendly cities.

Children's Park in Baiyun District, Guangzhou (Image source: China Guangzhou Release WeChat Account)

How can we build a child-friendly city? First, we need to define what a child-friendly city is. We need to know what indicators measure child-friendliness and what good examples exist both domestically and internationally. Today, in cities in high-income Western countries, children's playgrounds have become a "standard" feature. The central city of Barcelona covers an area of 102 square kilometers, with a population of 1.6 million in 2016, of which 8.4% are children under 10 years old. There are 513 children's playgrounds. The city council has a specific definition of a children's playground: an outdoor public space designed specifically for children's entertainment and equipped with dedicated play facilities for children. I found a children's playground quality indicator system (Table 1) from a professional book, which is worth our reference. Unlike the historical context described by Mumford, today's Western cities have many children's playgrounds. Nevertheless, Western planning scholars continue to focus on the issue of children's playgrounds, focusing on the spatial distribution of playgrounds, accessibility for different income classes and ethnicities, as well as the resulting spatial inequalities and differentiated childhood trajectories.

Currently, some cities in China have taken the lead in building child-friendly cities, such as Changsha, Hangzhou, and Shenzhen. But for the whole country, the task remains long. It is very necessary to build consensus, fully recognize the enormous socio-economic benefits of building child-friendly cities, vigorously promote child-friendly city development nationwide, and quickly address the shortcomings formed during the nearly 20 years of rapid development. The urgent task is to strive to increase public children's playgrounds in urban planning, construction, and renewal, creating a child-friendly and safe urban environment. China's "14th Five-Year Plan for National Economic and Social Development and the Outline of Long-Range Objectives for 2035" mentions "promoting block systems for new residential buildings." This is a very timely proposal that helps prevent the continued spread of gated communities in large buildings, while also promoting the provision and improvement of urban public space services.

The successful experiences of Western cities show us that building child-friendly cities is entirely feasible, and we have every means to do so.