The article deals with the problem of sustainability of modern cities in the context of the implementation of the concept of a smart city, the combination of the technologies of which acts as an innovative factor in the development of modern urban infrastructure. The characteristics of the main elements of the smart city, digital technologies used in its creation are given. The methodology and results of a comparative analysis of the urban digital infrastructure of the world's megacities in the context of COVID-19 are presented. The assessment of the global and Russian market of smart city technologies is given, trends and prospects of digital development of a modern city are identified as the most important factor in ensuring its sustainability. Recommendations are formulated for the development of solutions in the field of digitalization of urban space, taking into account the opinions of scientists and specialists in the field of management, socio-economic and humanitarian sciences. It is noted that efficiency and safety should become a priority in the implementation of smart city projects. © The Authors, published by EDP Sciences, 2020.