Abstract
Multi-layered sensor systems in future cities are not fully accessible through traditional metrological methods. The field of Systems Metrology accounts for that fact by shifting the focus from single sensors to those interconnected systems. The PTB Smart Metrology Campus (SMC) aims to investigate questions at different system levels, from data infrastructures, sensor networks and digital twins to the concept of human-as-a-sensor and data communication. The SMC and its projects will be introduced and linked to questions of the city system.