Urban open spaces have been gaining in significance in an unprecedented fashion in recent years. Their character, quality, state, and variability directly affect the development or, conversely, the decline of the urban environment, thereby directly impacting quality of life and the willingness of urban populations to identify with their surroundings. Open spaces also play an essential role in the sustainable development of cities. Following the condition of open spaces and continuing to support their development in areas which are found to be stagnating are imperative. These areas of potential worth and unique merit can be characterized and quantified. In the process, it becomes possible to continuously monitor the influence and effectiveness of planning measures on the quality of real spaces inside cities from the standpoint of sustainable development. Using a wide selection of sites, we will establish locally and universally applicable characteristics of urban open spaces, related to their historical, economic, ecological, and social potential. We will also attempt to demonstrate their immediate effect on sustainable urban development and quality of life. The results will contribute to the development of the theory of sustainable urban development and urban open spaces. This research endeavor is supported by funds from the Czech Science Foundation (GACR) 15-05237S: The Importance of Open Space for Sustainable Urban Development Project.