The paper reports the results of a stratigraphic reading on the northern façade of the Rocca di Novellara (Reggio Emilia, Italy), a castle which is now the town hall, right in the city centre. Though as a pole of the contemporary public life in Novellara, housing at present both a museum and a nineteenth century theatre, the Rocca recalls its military past through its name and by means of the still standing remains of the walls and corner towers. Besides a well-documented historical development, the stratigraphic investigation of the northern façade –the only part that still hasn´t been restored- allowed a direct observation of the material traces revealing the slow transformation of the Rocca from a fortification to a residential castle. This study gave the chance of understanding the different constructive phases of the castle, making a chronological sequence out of them but it was also meant to reflect about the changes of its character, as the building has been acquiring a complex identity through time, due both to high qualified architectural episodes and to as much meaningful though tiny changes. Thus, the permanence of the stratified marks can be regarded as one of the main goals of a preservation project.