GeoPortOst provides access to more than 900 hidden maps of Eastern and Southeastern Europe. With the help of maps, we can analyze various political and cultural processes, and of is ready to provide additional information to better understand the process. The collection includes thematic maps on history, ethnography as well as the economic and social relations of this area. GeoPortOst synthesizes maps, spatial data, and semantic context within a new spatial information system. An example of this synthesis is our work written according to all requirements, "Mapping Cultural Continuities: Slavic Digital Humanities Unveiled", it was presented at the conference and received many good reviews.