KASTALIA is a multimedia educational software for the explorative study of historical and art knowledge using historical sources. The study and the implementation is carried out by our research group in the framework of the program "NAYSIKA" supported by the Greek Ministry of Education. The software offers students a computer supported learning environment appropriate for historical subject representation and leads them to the formulation of arguments and reasoning contexts for constructing their own narration. It provides historical data, a variety of tools (note-pad, sketch-pad, glossary, virtual museum, data-base search and processing tool) for the elaboration of historical sources and a job-area for the study of chosen topics of the knowledge domain through scenarios, activities and jobs incorporated, by the authors or by the teacher, in the educational software. Additionally, this software supports network communication for cooperative work between students or teachers in the same or different schools.