Abstract— The problem of estimating the positions of landmarks using a mobile robot equipped with a camera has intensively been studied in the past. In this paper, we consider a variant of this problem in which the robot should estimate the locations of observed landmarks based on a sparse set of geo-referenced images for which no heading information is available. Sources for such kind of data are image portals such as Flickr or Google Image Search. We formulate the problem of estimating the landmark locations as an optimization problem and show that it is possible to accurately localize the landmarks in real world settings.