Currently, over 55% of the world's population lives in cities, and this is expected to rise to 68% by 2050, with nearly 90% of the increase in the urban population occurring in Asia and Africa. (For instance, the proportion of China's urban population has increased from 17.92% in 1978 to 58.5% in 2017).

The urbanization process has brought about the rapid socio-economic development of cities, yet its speed has also led to some development problems, such as over-consumption of resources, increasingly prominent pollution, frequent occurrence of 'urban diseases' and extreme weather events, continuous deterioration of living environment quality, etc., which have brought new challenges to sustainable urban design.

After experiencing three generations of historical paradigms including traditional, modernist, and green urban design, the technical concepts and methods of the practice have acquired some brand-new content with the increasing development of digital earth, smart city, internet, and artificial intelligence, further forming the fourth paradigm of digital urban design based on human-computer interaction.

This new paradigm takes the reconstruction of morphological integrity theory as the goal, the human–computer interaction as the approach, and the transformation of technical methods and tools as the core features.

Furthermore, digital urban design can play a key and supporting role in the preparation, implementation, and management of urban planning, highlighting the characteristics of history, culture, and landscape patterns, promoting fair and just social norms, and creating a livable and sustainable environment.

The digital city is one of the basic symbols of transformation from the industrialization era to the informatization era, which generally refers to the ability to effectively acquire, classify and store, automatically process and intelligently identify massive data in the category of urban natural, social, and economic systems.

Taking advanced information means to support the city planning, construction, operation, management, and emergency response can effectively improve the level of government management and service, and also promote the sustainable development of a city.

However, even if the fails we see in the pictures are becoming rarer, there's still the long-time conflict between urban development and historical protection.

Cities have been facing the dual challenges of renewal and decay, development and preservation. The general development trend of urban design for historical cities, historical blocks, and sections is to protect buildings and insert new ones through ‘weaving and patching’ on the premise of striving to preserve the original historical structure of the old city and the integrity of sections, thus forming an orderly progression of metabolism.

Overall, the enormous variety of types of projects on which planners work, the lack of consensus over processes and goals, and the varying approaches taken in different cities and countries have produced great variation within contemporary urban planning. Nevertheless, although the original principle of strict segregation of uses continues to prevail in many places, there is an observable trend toward mixed-use development—particularly of complementary activities such as retail, entertainment, and housing—within urban centers.

City planning as practice and discipline relies upon public policy as an instrument for producing a more equitable and attractive environment that, while not radically altering human behavior, nonetheless contributes to improvements in the quality of life for a great number of people. So let's hope that even a Twitter account dedicated to sharing memes can help raise awareness and engage the broader public in discussions about city planning issues.