In recent years, the hypothesis put forward by Artur Kowalik, concerning the mythical island of Bujan, had a real influence on the development by Wojciech Chudziak and his students of an interpretative model of such sites, according to which they were to be places implementing the idea of „axis mundi". A detailed analysis of several sites, based also on data from written sources, allows us to argue for the view that at least in the 11th and 12th centuries, on some lake islands in the area of North-Western Slavdom, there were places of pagan worship with shrines. A detailed interpretation of some deposits placed in the water at the shores, an analysis of sociotopographic indicators within the islands or information provided by chroniclers, allows us to propose a model of such sanctuaries. Moreover, it can be proven that such places were a kind of anchorage for the rulers.

The aim of this paper is to present the cultural phenomenon of the form of specific stronghold complexes located on lake islands in the South Baltic Lakeland. Their functional interpretation, based on both written and archaeological sources, allows us to consider them as places where elite armed men, noblemen, and in some of them also members of dukes families resided. Some of these sites fully meet the criteria of a complex central place, as set out by Eike Gringmuth-Dallmer, adapting Walter Christaller's central place theory for the needs of archaeology. The most outstanding example of such a site is Ostrów Lednicki; apart from it, however, one can indicate quite a large group of analogous sites on both sides of the Oder. The peak periods of construction and use of such sites coincided exactly with the formation of early states in the area of North-Western Slavdom, which seems to be no coincidence.