The article addresses issues related to the development of Smart Cities and Smart Sustainable Cities. The authors draw attention to the important role of social capital, emphasising the participation of citizens in the holistic management of modern Smart City. This approach allows one to show the development of cities in a wide context of sustainable development. The authors refer, inter alia, to Agenda 21, The Future We Want, and international programmes, such as the Sustainable Cities Programme of Habitat (UNEP) or Healthy Cities Programme of the WHO. The authors indicate that social capital is an element integrating particular parts of the urban system. They also indicate that the development of modern technologies will lead to the formation of a new type of society 4.0., advancing along with the development of industry 4.0 and artificial intelligence. In order to properly use the opportunities related to the development of modern technologies, society should be properly prepared for using their functionalities.