Landmarks are crucial elements in how people understand and communicate about space. In wayfinding they provide references that are preferred and easier to follow than distances or street names alone. Thus, the inclusion of landmarks into navigation services is a long-held goal, but its implementation has largely failed so far. To a large part this is due to significant difficulties in obtaining a sufficient data set of landmark candidates. In this paper, we introduce a mobile application, which enables a user-generated collection of landmarks. Employing a photo-based interface, the application calculates and ranks potential landmark candidates based on the current visible area and presents them to the user, who then may choose the intended one. We use OpenStreetMap as data source; the app allows tagging OSM objects as potential landmarks. Integrating users into the landmark selection process keeps data requirements low, while a simple interface lowers the burden on the users.