The OPENCities Monitor provides access to city profiles, several benchmarking opportunities and best-practice examples. Overall, cities receive an immediate and easy to use insight of their strengths and weaknesses how open they are and advise to improve their policies towards openness and diversity. Openness cannot be observed or measured directly. It is a multi-dimensional and very complex phenomenon. However, there are many aspects of openness that can be observed and measured. The OPENCities monitor includes 54 internationally comparable indicators, aggregated into 11 areas. The city can attain values above or below 100. Values below 100 indicate that the city is less open than the city sample. Values above 100 signal that the city is more open than the city sample.