The Circular Helical Staircase at Palazzo Spada

Abstract

The paper deals with the unpublished survey and geometric analysis of the circular helical staircase built around 1660 in Palazzo Spada’s wing on Via del Polverone in Rome. Its role in the development of the place and the history of its design process are addressed thanks to historical drawings and the reference model proposed both in the treatise and construction between the fifteenth and seventeenth centuries. A description of the 3D digital survey procedures is followed by the reconstruction of a NURBS 3D model that describes the staircase and its geometric properties.