Many urban or environmental models are determined with the objective to help practitioners and stakeholders in the processes of decision making. The models represented in 3D dimensional geometry are elements of a city and are called 3D models cities. In a wide range, these models are more and more being used for different cities and countries, for purposes beyond simple visualization. Possibility of using of this kind of models, in introducing semantics as geometric aspects, leads into enriching the semantics of 3D city models. Furthermore, in the perspective of sustainable development, cities should be studied in thorough and comprehensive way, taking into account inter relation of many different questions and problematic issues that are related to the future development of urban areas. This can be achieved through the identification and utilization of knowledge about the data and the models, too. The use of ontology is a powerful way to reach the semantic enrichment of 3D city models and also their interoperability with other urban models, so that they become an effective matrix of urban knowledge with a perspective of sustainability. This action will enable: (1) Integrative platform based on semantics enrichment of 3D city models, (2) Use of ontological methodology that can be reused, (3) Evaluating the usability of integrative platform for planning and decision making.