Abstract
Revitalization activities of historical buildings, especially those with several hundred years of history require solving many problems of conservational nature especially issues related to preserving the authenticity of the existing tissue, ways of reconstructing lost elements but most of all connecting historical architecture with contemporary elements. Moreover, changing the function of a building with a great historic significance (even partially), is often a difficult task that requires thorough recognition and understanding of the history. The adaptation of the Archcathedral Basilic in Frombork attic for museum and exhibition purposes provides excellent material for future ventures in medieval structures. In the article, spatial and technical solutions, design assumptions, and the process of the preparation and realization of the investment were examined. The objective of this study is to present a methodology for the revitalization of architecturally and historically valuable buildings, one that aligns with international conservation standards, respects the integrity of the historical substance while ensuring adherence to current functional and safety regulations.