This work presents the developments of representing a part of the city districts of Manchester, UK and Turin, IT initiated within the FP7 DIMMER project completed in 2016 and continued in the last years by the Center of Excellence GIS of CSI Piemonte. The DIMMER system integrates BIM (building information modelling) and district level 3D models with real-time data from sensors and user feedback to analyze and correlate buildings utilization and provide real-time feedback about energy-related behaviors. The emerging standard 3D Tiles endorsed by the OGC was applied to represent CityGML data of two districts of Turin, Italy and Manchester, UK. 3D Tiles allows for a high level of detail (LOD) visualization that displays increasing detail of geometric features and their alphanumeric properties. Currently, the OGC 3D Tiles technology is mature, and the OGC CityGML specification will be soon updated to version three, with the adoption of exciting innovations like the support of time-dependent properties defined Dynamizers.