The Regnum Francorum Online (RFO) geographical information system explors new possibilities in digital humanities and in particular, medieval history and diplomatics, as a response to, and taking advantage of the growing number of digitized sources available online, and especially, the possibility to reference even individual documents within source-editons, using persistant identifiers (URI). Source documents in this context, refer primarily to charters, however, narrative sources, coins and inscriptions are also considered for inclusion in the database. The database extends into Late Antiquity to give the necessary historical background to medieval civilization. The long term goal of the database project is to reference (all) source-documents of Merovingian and Carolingian Europe, regarding properties of the documents themselfes (authencity, origin, edition) and evidence of historical events, found within them. Properties of events, such as time, location, agent and aim are compiled within the database, together with evidence of medieval entities such as place, institution, territory, personal names and person, mentioned in the events. The database application renders two-way interactive maps based on the meta-data of documents and events, respectively, together with background layers of medieval territories, roman roads, modern extension of forest, and other features relevant to historical analysis. This makes it possible to visualize on maps the distribution of documents with different characteristics, and the itinerary and activities of rulers, development of posessions of institution, extension and change of territories, in time and space. Meta-data can also be visualized thematically, e.g. the distribition of fiscal property, of churches and monasteries, etc. RFO contains historical information about 14,000 places, 1,500 institutions, 600 medieval territories, and other entities, in the realm of the Frankish kingdom/empire. This far, 18.000 source-documents have been referenced and analyzed. For the purpose of inter-linking and embedding external documents and maps into the RFO-gateway, identifiers of external source-documents are maintained within the database as they become available on the internet. This way, it serves as a geographical gateway to scattered online sources.