<p>This paper examines the relationship between geometry and architecture in Guarino Guarini's design and building activities. The study was performed using methodologies that integrate and interconnect analyses, redrawings, and interpretations. A case study of the double staircase of Palazzo Carignano was performed by comparing autograph drawings with a building survey. Redrawing of the original plates and visual programming language modeling of the point cloud section enabled thorough comparison between the ideation and construction phases. The analyses shed new light on different original drawings to explore the Guarinian design process. The link between geometry and architecture is evident in not only his theoretical works, but also his design method and realized buildings.</p>