Updating and developing existing cities is more sustainable and practical than building new ones. New cities often lead to urban sprawl, environmental degradation, and high costs while diverting resources from needy areas. Existing cities already have infrastructure and cultural value that can be revitalized to meet modern needs. Enhancing urban systems and prioritizing underserved communities promotes equity and sustainability. Retrofitting cities reduces environmental impact and supports efficient resource use, addressing urban challenges without sacrificing ecosystems or increasing carbon emissions.

Developing new cities or towns might be cheaper to local government than redeveloping existing cities because the latter involve demolition through eminent domain. It is so in China, where all urban land is owned by the state and rural land is owned by peasant collective. Given the development of new cities or development zones, many Chinese cities now feature a dual-centric urban structure. Problems such as urban sprawl, ghost town or excessive commuting ensue.

Il serait mieux de moderniser et développer les villes anciennes pour plusieurs raisons:

-On pourrait sauvegarder le patrimoine architectural

-Limiter l'exploitation excessive de la terre surtout agricole qui est entrain de se dégrader et d'être grignoter par l'extension urbaine il faut penser au développement durable et penser aux générations futures qui auront besoin de l'eau et du sol pour cultiver

New cities, which are often endowed with some form of special economic zone status, and are targeted towards specific industries, can become new hubs that are far more attractive to potential investors and entrepreneurs, with better policy regimes and infrastructure support, than existing cities.

Updating existing cities takes advantage of sunk costs in both infrastructure and cultural amenities.