Between spatial and archival data: digital humanities for the history of a staircase of Pitti palace

In the last decades, surveys produced with geomatic techniques are increasingly used for the study and conservation of the built heritage because they automatically collect large amounts of data with an accuracy and objectivity that could not be achieved with traditional techniques. As in other fields of digital and spatial humanities, the combination of spatial data with archival and secondary sources provides new tools for reconstructing the history, construction, and transformation of a historic architecture. The new digital survey of Pitti Palace, which was carried out between 2019 and 2021, has revealed aspects neglected by previous surveys and historical studies. Pitti Palace is the largest historical civil building in Florence. In the 16th century, Bartolomeo Ammannati carried out important extensions, including the so-called "spiral staircase", one of the most important staircases in the palace. This staircase, of which there is little documentation, although it is considered a masterpiece, was demolished at the beginning of the 19th century by Pasquale Poccianti to make way for the "New Secondary Staircase", on which previous studies have focused mainly on stylistic and decorative aspects. Using digital spatial data as a primary source, the research aimed to explain the construction history of the new staircase built by Poccianti, allowing a precise comparison between the archive documents and the actual geometry of the building elements. It also highlights previously undocumented features, including the evidence for the Ammannati staircase and the important changes made during the construction of the new staircase. The article shows how the insertion of the new staircase profoundly altered the design, structure and layout of a wing of the Pitti Palace. It also suggests how a more transdisciplinary and holistic approach helps the study of historical architecture.