Over the past 20 years, an enormous geodata infrastructure has been built up in the city of Zurich. More than 500 data sets provide a comprehensive, digital image of reality. The city of Zurich is increasingly using digital twins to tackle specific issues and processes. In an urban context, a digital twin can offer a major advantage over traditional geodata infrastructure in a wide range of tasks. Various examples of digital twins will be presented in the presentation along with some organisational and technical basics.