The Grand Staircase of the Birago di Borgaro Palace: From Digital Model to physical scale model for the communication of construction aspects

The combined use of digital and physical models promotes inclusive communication and represents an important medium for presenting heritage to the community, particularly to the tourism sector. The work presented here concerns the Grand Staircase of the Birago di Borgaro Palace in Turin, designed by Filippo Juvarra and built from 1716 onwards. The monumental staircase is located near the main atrium; its development takes place on three right-handed ramps leading to the main floor hall. The contribution focuses on the application of digital technologies for three-dimensional modelling and digital fabrication, aimed at studying and communicating the constructive aspects of architectural heritage. The adopted methodology involves the use of data from previous acquisitions and restitutions (TLS survey by Prof. M.C. López González, two-dimensional drawing by Arch. F. Natta) for the digital modelling of the Grand Staircase in order to retrace the formal ideation process related to the applied construction techniques. Starting from the virtual model, through digital fabrication techniques, a physical model is created on a 1:50 scale, composed of four main blocks obtained using three vertical section planes. The model, in addition to restoring the compositional apparatus of the decorations, aims to make understandable, explicit and readable the construction system used in the design: on the one hand, it restores the overall three-dimensional morphology of the artefact, and on the other, it offers the possibility to be explored revealing the structural composition through the constituent elements such as the ramping barrel vaults, the cross vaults that support the landings and the stiffening arches. The physical model of the Grand Staircase of the Birago di Borgaro Palace is an example of how the physical representation of the built space can become an expression of layered and sedimented information, lending itself to the communication of knowledge even to a non-expert audience.