The Circular Helical Staircase at Palazzo Spada

Abstract The paper deals with the unpublished survey and geometric analysis of circular helical staircase built around 1660 in Palazzo Spada’s wing on Via del Polverone Rome. Its role development place history its design process are addressed thanks to historical drawings reference model proposed both treatise construction between fifteenth seventeenth centuries. A description 3D digital procedures is followed by reconstruction a NURBS that describes properties. Three turns undergo an in-depth slope angle lines. This leads recognition main features this staircase: unique central structure; implementation geometrical proportions descending from Andrea Palladio’s treatise; changes characterize flights space they generate.