The article discusses how 3D city models are used to represent urban data in a unified way. The researchers focused on creating a detailed 3D model of a neighborhood in Sofia city using the CityGML standard. They looked at similar models from 18 cities to improve their modeling techniques. The study found that modeling buildings with separate parts is more effective than as a single solid. The researchers also explored how to visualize the model in popular platforms like ArcGIS Pro and Cesium Ion.