The Main Market Square in Cracow underwent numerous transformations during the course of the seven centuries of its existence; two phases, however, i.e. during the sixteenth and the nineteenth-twentieth century were decisive for its actual shape and became the key for contemporary conservation. For many years, the author conducted research into the mechanisms and outcome of those transformations by basing himself on analyses of the results of interdisciplinary investigations, confronted with cartographic and iconographie material. This procedure enabled him to reconstruct the complicated stratigraphy of the Main Market Square and to distinguish its oldest mediaeval architectural relics, at present inaccessible, but preserved in a degree which makes possible their full theoretical reconstruction as well as the exhibition of ancient strata preserved under the surface of the Square. Results of research presented in the report provide a premise for an attempt to penetrate the relics in question and for preparing a project which would render accessible and display elements of extant mediaeval architecture in Cracow.