Location-Based Services (LBS) are more and more commonly accessed through PDA or smart phones. As portals deriving of services delivered by a unique provider are easy to define, the objective of this paper is to address the problem of generating portals allowing the accesses of services provided by several companies. In other words, the goal is to generate automatically a unique visual multi-provider portal in a context of portal interoperability. After the analysis of examples in order to define more clearly spatial concepts such as reference location and scopes of services, various organizations of portals are examined, namely text-based, icon-based, map-based and street-view. We conclude this paper by recommending map-based and street-view systems, together with XML extensions which must supplement LBS metadata in order to generate those visual portals.