Ottant’anni di studi e ricerche sul Campanile della Cattedrale di Pisa: le commissioni ministeriali e Piero Sanpaolesi

The contribution reconstructs eighty years of studies, investigations, and institutional initiatives concerning the stability of the Leaning Tower of Pisa, from the establishment of the first ministerial commission in 1907 to the closure of the monument to the public in 1989. The study examines the succession of technical and scientific commissions appointed to investigate the Tower’s inclination, foundation soil, groundwater regime, structural behaviour, and possible consolidation strategies. Although these bodies produced an extensive body of geological, geotechnical, hydraulic, and structural research, many proposed interventions remained unimplemented because of technical disagreements, institutional conflicts, or concerns about their impact on the monument. Particular attention is devoted to Piero Sanpaolesi, who became involved with the Tower as Superintendent and, from 1949, as a member of the post-war ministerial commission. His activity included the conservation of war-damaged marble elements, historical and archival research, structural interpretation, and critical engagement with proposals for straightening or consolidating the monument. Sanpaolesi consistently maintained that the principal problem lay not in the masonry structure itself but in the behaviour of the foundation soil. His interpretation, based on the combined study of historical documents, construction phases, materials, and structural evidence, was substantially confirmed by the later stabilisation works. The essay presents his approach as an exemplary application of the principle that the monument is a document of itself, requiring interdisciplinary investigation and continuous critical comparison with the physical fabric.