The article presents the conceptual assumptions of the Smart City in its different phases of development - Smart City 1.0, Smart City 2.0, Smart City 3.0, Smart City 4.0, Smart City 5.0 and Smart Sustainable City. With reference to „Transforming our world: the 2030 Agenda for Sustainable Development” containing 17 Sustainable Development Goals, the article specifically presents the assumptions and practical solutions for SDG Goal 11. A critical analysis of the literature on the subject and a content analysis of the SDG reports revealed a juxtaposition of the diverse capabilities of smart technologies and their insufficient implementation to meet the Sustainable Development Goals in Smart Cities. The reality is not encouraging. The population of people living in slums is growing rapidly, social inequalities are widening, and there is a lack of access to convenient urban transport. There is chaotic urban sprawl, air pollution and insufficient public open spaces. Solutions to urban problems are often interventionist rather than preventive. The rational and sustainable use of modern technology can change this.