The capture and description of the numerous 'places' found in urban environments could enable the deployment of seamless mobile and location-aware social navigation tools. Unfortunately, we are limited in our approaches to systematically capture place data at the requisite level of granularity or how to obtain labeling consensus. We explored this issue through 'research through design', developing and deploying the MarkIt mobile phone game, which aimed to engage a community of users in place description. In this paper, we present our design rationale and the game's design. We then highlight how key innovations instantiated in MarkIt resulted in rapid data generation of both images and location related labels.