For citizens, being aware of what is happening in their urban surroundings becomes challenging as more information from diverse sources becomes available. In this paper, we describe our user-centered approach of designing an interactive tool making use of urban data visualisations to facilitate people’s decisions about social and cultural events. After gathering the needs of urban actors through formative user studies, we identified beneficial data types and collected a variety of data sets from publicly accessible online sources. For the aim of enabling casual exploration of events in the city, we designed a set of geovisualisation prototypes and designed a variety of evaluative user studies based on established geovisualisation techniques. The main aim here is to enable casual exploration of events in the city more than the intended search for specific events. We developed two prototypes that make use of two different geovisualisations to represent events: Prototype A uses common location markers, and prototype B uses a novel glyph design to visualize more types of data at a glance. We share the lessons learned from the results of our study, which will inform the design of geographical data visualisations for citizens.