So far, we have underlined the important role of cities (and their citizens) in co-creation and in the development of sustainable solutions. However, we still do not know how the labour of cities in this context can be compared. For this, several city rankings that rely on different indexes exist. The video below presents some of them and outlines the importance of acknowledging that each different ranking may cover certain areas of the world, and also may use different indicators to assess the sustainability of cities. A reason for these differences between rankings and their indexes might also be that different organisations promote different rankings, hence giving importance to different aspects. Finally, it might also be due to the fact that rankings usually reflect a certain, fixed moment in time.