This paper proposes a study approach to the city as composition of layers, each layer presenting some characteristic aspect of the city based on some type of ontological classification. Traditional analysis and functional views of cities offer only a partial, and sometimes misleading, understanding of the city because such methods tend to modularize the city without modelling its complexity. By taking an ontological perspective we aim to develop integrated ontological models. Moreover, we give a look at the subjective knowledge of city inhabitants. This kind of knowledge is not always valorized in traditional scientific approaches. Yet it is essential for understanding whether a change can be embraced and sustainably supported by the agent community, the living component of the city system. The present work aims to explore a different modularization approach where the city is seen as an integrated system that should not be subdivided in different ways depending on the type of problem one aims to solve. Indeed, one can meaningfully divide the city into parts only taking into account the nature of these entities and of the connections they form. Without analyzing the structural and dynamic organization of cities, their processes and composing objects, any decomposition of the city would likely miss critical interconnections and dependencies. The final perspective is to build a general ontology-based framework aimed at creating a new generation of knowledge-based models and tools for city modelling and simulation, more oriented to sustainable planning.
