This study aims to investigate modernity and postmodernity conditions and hierarchies of Turkish cities. The conceptual framework of modernism and postmodernism concerning space has been discussed, and it has been tried to develop indicators suitable for the quantitative analysis of the modernity/postmodernity conditions of the cities. The post-1990 Turkish Socio-Economic Development Index (SEDI) data sets were used as secondary data, and a new set of indicators was developed to rank the levels of modernity and postmodernity hierarchies of cities. 12 criteria defining modernism and 22 criteria defining postmodernism were determined under the headings of "organizational/managerial", "economic", "social/ethical", and "spatial". Cities are clustered by evaluating 34 criteria obtained by Principal Component Analysis (PCA) and Cluster Analysis methods. The method used here, and the field research findings are candidates to fill the gap in understanding modern and postmodern urban space in Turkey and are expected to contribute to balanced urban development and hierarchy studies in the field of city and regional planning in future studies.