A remarkable series of medieval drawings in Strasbourg documents the emergence of the local cathedral workshop as a major center of Gothic design around 1300. The so-called Plans A and B, in particular, figure prominently in the literature on Gothic architecture, but the formalistic methods usually brought to bear on the drawings leave many questions unresolved. This article uses geometrical analysis to show how the proportions of both drawings resulted from the compass-based Gothic design process. This discussion reveals a striking difference between the essentially planar Plan A and the more three-dimensionally conceived Plan B, in which the octagonal plan of the intended spire played a crucial generating role. Geometrical analysis of the complete façade block, meanwhile, shows that Plans A and B continued to influence the façade builders in the fourteenth century, despite the introduction of a new ground plan shortly before the beginning of construction in 1277.

This study sets out to test assumptions about openwork flying buttresses of the type used in Gothic buildings from the mid-thirteenth century. The employment of such units has been associated with the "decadence" of Gothic architecture. Arguing that the deployment of the first such flyers responded to special circumstances at each of the buildings in question, the authors proceed to test the structural performance of the newfangled flyers of the Amiens choir and to correlate the findings with an archaeological investigation of the edifice itself. The openwork flyer is thus placed within a broadly conceived framework of theory and practice.