Today, many cities have at their disposal a digital model useful in many applications such as decision making in urban planning. 3D data representing objects in the city such as land and buildings often comes from successive acquisition campaigns. Unfortunately, digital models of cities can have many versions of the same area. Having tools to detect changes becomes a necessity. It is then possible to highlight any differences between multiple versions of the same area in 3D. A second application can be related to the possibility of making a temporal representation by taking into account the detected changes. In this paper, we propose a set of tools to detect changes. The use case is done on buildings. Our method is based on CityGML and cadastre files. The output is a CityGML file containing a representation of the evolution over time of the objects in the city.