The paper presents preliminary results in the area of ontological engineering for historical research. Historical information systems are still in the initial stage of development. Our experience hitherto shows that the decisive stage in the development of such systems is a conceptual model and ontological engineering seems to be the right tool to build it. Our particular aim is to develop a database system for the history of the administrative structure of the Catholic Church in Central-Eastern Europe in the so-called pre-statical period, ie roughly from XII to XIX century. We use DOLCE as a foundational ontology, especially its part concerning social objects. We build an axiomatic system that formally defines the basic notions of those structures and may be interpreted as the conceptual scheme of this database.