This publication advocates a “cities-based” approach to sustainable development, which recognizes the central and integrating role that cities and urban living play in developing sustainability. The publication highlights that, similarly to the financial crisis of 2008, the COVID-19 pandemic has shown how different cities have different capacities to cope with crises. Both the pandemic and the economic crisis caused by lockdown measures have disproportionally affected different cities as well as different groups of the population, with the most vulnerable groups of society suffering most. The pandemic has also demonstrated that cities need to develop innovative methods to confront infectious diseases without relying on drastic top-down measures such as lockdown restrictions. Instead, cities need to use innovative and sustainable measures, including within urban design and planning, to establish green public spaces and other nature-based solutions.