Urban Computing is a branch of Pervasive Computing that investigates urban settings and everyday lifestyles. A lot of information to develop pervasive applications for urban environments is often already available, even if scattered and not integrated: maps, points of interest, user locations, traffic, pollution, events are just a few examples of the digitalized information which we can access on the Web. And applications for mobile users that leverage such information are rapidly growing. In this paper, we report our experience in applying techniques developed by the Semantic Web and geo-spatial communities to Urban Computing application development. We refer to the early achievements of the LarKC project, in which we developed the described demonstrator. We highlight the positive sides of our experience and we discuss open issues and possible advances.