This paper presents completed research in phase one of a project into the interdisciplinary co-design and collaborative uses of social media in urban settings. Research now includes place-specific computing, locative media applications (‘apps’), and open source tools (OpenStreetMaps, Ushahidi). While studies exists on locative technologies with implications for urban planning and collaboration, there is little research on the designs of locative apps for ‘cultural mapping’ in city settings. Following the themes of Re:Search, we investigate ways the design of a mobile app may mimic, change and transform earlier paper-based approaches to experimental urban mapping, namely the Urban Gallery Methodology. In terms of design, through co-creation and its critical reflection, we address the challenges and realisations of transposing this method to mobile social and locative media. We discuss the potential of social media to enhance urban studies and the domain of cultural mapping. We argue for greater attention to co-design and the relation between the development of such apps and their situated use as part of an ongoing user-related wider design and mapping process. We conclude that apps need research about both their design and contexts of use.