Deepening the knowledge of military architecture in an urban context through digital representations integrated with geophysical surveys. The city walls of Cagliari (Italy)

This paper shows some results of a multidisciplinary study including digital surveys integrated with geophysical investigations. The procedure is applied in the city of Cagliari, Italy, in the area of the ancient walls between the bastion of Santa Croce and the fourteenth-century Elephant Tower. This sector consists of the curtain of Santa Chiara, designed in 1575 and completed in the years 1576-1578 by the military engineer Giorgio Paleari. The archival documents offer precise indications on the collapses and the reconstructions/expansions that took place in that period, so facilitating a recognition of the events. Compared to the medieval walls, the work of Paleari brought forward the line of defense by means of a robust embankment and incorporated two of the fifteenth-century towers described in the drawings of the military engineers of the time. In the eighteenth century, the front was completed with the construction of a lowered embankment leaning against the southern side of the bastion of Santa Croce and the curtain of Santa Chiara. More recently, both the bastion and the sixteenth century curtain have been reinforced by means of several restoration and consolidation works. The latter changed the profile of the parapet –in the origin it was inclined-and the static balance of the constructive system by means of reinforced concrete piles. The survey methods and techniques used in this study provide interesting information about the current structure of the bastion system, such as the presence of vaulted passages functional to the military work. A further study campaign mainly based on seismic tomography techniques is proposed.