Many urban or environmental models are defined with the objective of helping practitioners and stakeholders in their decision-making processes. Models which represent in 3 dimensions the geometric elements of a city are called 3D city models. These models are increasingly used in different cities and countries for an intended wide range of applications beyond mere visualization. Such uses are made possible by adding semantics to the geometrical aspects, leading to semantically enriched 3D city models. Furthermore, in the perspective of a sustainable development, cities ought to be studied in a comprehensive manner taking into account many interrelations between various urban issues. This can be achieved by identifying and extracting the knowledge underlying in related data and models. Using ontologies is a robust way to achieve the semantic enrichment of 3D city models as well as their interoperability with other urban models, so that they become an effective matrix of urban knowledge in a perspective of sustainability. This Action will (1) create an integrative platform based on semantically enriched 3D city models, (2) use an ontology-based methodology that could be reused (3) assess the usability of the integrated platform for planning and decision-making. Keywords: 3D city models, semantic enrichment, ontologies, interoperability
