The double staircase of Palazzo Carignano: geometric studies among drawings, survey, and algorithmic modelling

The double staircase of Palazzo Carignano represents a unicum in the panorama of Baroque architecture and is an essential element in the definition of the building’s conformation in the Guarini design process, which ended with its construction in 1679 (Lange,1970: 171). It engages in a close formal dialogue with the fulcrum of the composition constituted by the atrium and the main hall above it (Portoghesi, 2024: 35), as well as the other rooms connected to the ceremonial route: the entrance hall, the side vestibules, and the vestibule leading to the main hall. The research outlined in this proposal is rooted in a broader project focusing on the physical and cognitive accessibility of the palace, which was commissioned by the Direzione Regionale Musei – Museo di Palazzo Carignano. The study investigates and interprets the geometric shape of the staircase layout from design to construction by comparing some autograph drawings and a digital survey of the building. An analysis and graphic reconstruction of the drawings of the staircase will be performed in relation with the entrance hall, atrium, and vestibules to examine hypotheses about reconstruction of the traces on the ground. These endeavors are made possible by the interpretation of point cloud sections and allow us to highlight the variations that have occurred between design and construction. In addition, algorithmic modeling tools could suggest new construction analysis methods.