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).