This policy brief explores the potential of local digital twins for data-supported decision making in a time when cities are under pressure to deliver more sustainable policies, optimise service performance and grow local economies, all while keeping people safe, reducing budget spend and managing a wide range of socio economic challenges. DUET (Digital Urban European Twins), a European innovation initiative, transferred the concept of digital twins from an industrial setting to the public sector domain creating a technology called Local Digital Twins (LDT), also known as urban digital twins. Replicating a city's physical assets, processes and systems using data, analytics and machine learning, DUET created virtual replicas of the cities of Athens, Pilsen and the Region of Flanders that automatically updated and changed in real-time as the physical cities themselves changed. This policy brief features a quick-start digital twin maturity model, alongside three key policy recommendations using the experience of DUET to inspire and encourage European cities to start their own digital twin journeys.