Cities are about to enter a pivotal period in their development, when digital creations will no longer only depict real-world urban settings but will also start to influence them, predict how they will change, and work alongside humans to co-create futures. The convergence of urban digital twin technologies and generative artificial intelligence (AI) lies at the heart of this change (Lifelo et al. 2024), opening up new possibilities for how we plan, manage, and revitalize our cities.