The ‘Regular Fortress’ by Guarini and the Citadel of Turin

In his Trattato di Fortificatione, Guarino Guarini described and drew a pentagonal bastioned scheme as an ideal ‘regular fortress’. The closely connected geometry, architecture, and ballistics in the drawing form a true fortified system. Guarini draws his experience from knowledge of military architecture in Italy, Flanders, and France. He was in Turin when he wrote the treatise, so it could be hypothesized that the Citadel of Turin was one of his references. Using the tools of graphical analysis and history of representation, the aim of this paper is to identify Guarini’s models for the regular fortress and the points of divergence between his theorization and the Citadel of Turin as they appear in several archival drawings.