Spatial database systems built on top of distributed and heterogeneous spatial information sources such as conventional spatial databases underlying Geographical Information Systems (GIS), spatial data files and spatial information acquired or inferred from the Web, suffer from data integration and topological consistency problems. These issues make the globally-integrated spatial database incomplete, so that effectively and efficiently answering range queries over such databases represents a leading challenge for spatial database systems research. In- spired by these motivations, in this paper we propose I-SQE (Spatial Query Engine for Incomplete information), an innovative query engine for answering range queries over incomplete spatial databases via mean- ingfully integrating geometrical information and topological reasoning. I-SQE finally allows us to enhance the quality and the expressive power of retrieved answers by meaningfully taking advantages from the amenity of representing spatial database objects via both the geometrical and the topological level.