Despite prior efforts to solve urban problems and build smart cities using large-scale urban information, researchers have yet to develop tools for city administrators to easily access a diverse mix of city information. To address this limitation, this article proposes an augmented reality visualization system, GeoACT, which can develop a digital twin to present city information from both macro and micro perspectives. GeoACT employs a 3D virtual city miniature with real and virtual IoT information to provide a macro perspective view, and a 360-degree-video-based visualization technique is used for a micro perspective view. We applied GeoACT to an urban space and demonstrated that it could effectively visualize city information through an augmented reality Head Mounted Display (HMD). Furthermore, GeoACT can be used in urban control centers.