The growing importance of maturity smart cities is currently observed worldwide. The vast majority of smart city models focus on hard domains such as communication and technology infrastructure. Scientists emphasize the need to take into account social capital and the knowledge of residents. The smart cities invest in enhanced openness and transparency data. Mature smart cities use real-time evidences and information to citizens, businesses and visitors. The smart cities are characterized by bottom-down management and civil government. The paper aims to assess the urban smartness of selected European cities based on the ISO 37120 standard. Several research methods including the Multidimensional Statistical Analysis (MSA) were applied. Using the statistical analysis of European smart cities with the implemented ISO 37120 standard, the author tried to fill gaps in the knowledge and to evaluate maturity smart cities. The results of the research have shown that the smart city concept is a viable strategy which contributes to the urban sustainability. The author also found out that urban sustainability frameworks contain a large number of indicators measuring environmental sustainability, the smart city frameworks lack environmental indicators while highlighting social and economic aspects.