Local governments had key and prominent roles in tackling the COVID-19 pandemic. Their task was to take short-term measures quickly and to organize protection and care for those in need. The main objective of our paper is to present how local governments communicated with their inhabitants on various online interfaces in this crisis situation. Our analysis covers 54 settlements representing all the different levels of the settlement network from large cities to small villages. We examined the webpages and Facebook pages of local governments and mayors, first during the first wave and then during the second and third waves of the pandemic. Recognizing their responsibility, local governments clearly tried to provide information to the inhabitants as quickly as possible. They considered the online interfaces the most effective, but the online communication had typically been complemented by information published on more traditional channels as well. There were no significant differences in terms of the way and characteristics of communication among the different types of settlements, although local governments of different sizes obviously had to face different challenges in terms of the amount of tasks they had to tackle. The communication process was a very difficult task because of the lack of information and the not-transparent data provision. Even on the Facebook pages especially suitable for this purpose, interactivity rumbled, and in many cases the questions and suggestions of the inhabitants remained unanswered. It is instructive that, with few exceptions, settlements do not place emphasis on surveying local needs and opinions.

As more and more people live in cities, the problems of sustainability affect an increasing number of urban dwellers. Cities are extremely exposed to the consequences of climate change and can also be considered as one of the centres of human activity contributing to climate change and other environmental problems. Rapid urbanization affects all aspects of sustainability, environmental, economic and social, such as the growth of slums (or people living in poor housing conditions), increasing air pollution, noise pollution, urban heat islands, problems with water management and supply, inadequate basic services and infrastructure, and unplanned urban sprawl, which make cities even more vulnerable to disasters. However, with good urban planning and management, the world's urban spaces can become inclusive, safe and sustainable, and dynamic hubs of innovation and enterprise. Therefore, further investigation of the relationship between urbanization and the environment is of fundamental importance both for reducing human impact and for adapting to challenges of sustainability. Responsible development and perpetration of smart megacity results and technologies could contribute to the progress toward sustainable development pretensions. Technologies can serve as great opportunities for achieving sustainability, but at the same time can be also threats (e.g. through high energy demands).