La cinta muraria di Pisa: studi preliminari per il progetto di restauro

The contribution presents the preliminary investigations conducted on the surviving western section of Pisa’s southern medieval walls, between the Stampace Bastion and Via Silvio Pellico. Unlike the northern and eastern sections, this portion was not included in the earlier programme for the conservation and enhancement of the city’s fortifications. The research reconstructs the complex historical development of the walls, erected from the mid-twelfth century and subsequently modified through repairs, additions, demolitions, and adaptations. Particular attention is devoted to the transformations caused between the late nineteenth and early twentieth centuries by tramway and railway infrastructure, including the demolition of approximately sixty metres of wall and the construction of buildings and tracks adjoining the monument. The knowledge process combined archival and iconographic research with laser-scanner and photogrammetric surveys, stratigraphic analysis, in situ investigations, and laboratory characterisation of stones and mortars. The study identified the different construction phases and materials, including San Giuliano limestone, Asciano breccia, brickwork, and lime-based mortars. The main conservation problems include invasive vegetation, ineffective rainwater drainage, dampness, biological colonisation, erosion, material loss, and traces left by demolished structures and obsolete installations. Structural analysis also revealed an outward deformation extending for approximately seventy metres, with a maximum displacement of about forty centimetres, as well as a widespread crack pattern associated with material deterioration and discontinuities between different masonry phases. The resulting thematic documentation provides the basis for securing, conserving, and enhancing the walls within the wider redevelopment of the area as the Sesta Porta urban park.