The eighteenth-century full-scale tracings in the church of Saint Clare in Santiago de Compostela: execution drawings or design sketches? José Calvo-López Universidad Politécnica de Cartagena Miguel Taín-Guzmán Universidade de Santiago de Compostela Idoia Camiruaga-Osés Consorcio de Santiago Abstract In August 2014, a large set of full-scale architectural tracings was found in the floor of the convent church of Saint Clare in Santiago de Compostela, inscribed in a granite base, beneath a wooden floorboard that was being renovated at that time. The ensemble is larger than any other set of architectural full-scale tracings from the Early Modern period found up to this time, and is clearly connected with the entrance building of the convent, constructed in 1719- 24, including drawings for the most important elements in the building. Both the tracings and the entrance façade have been surveyed using topographic and photogrammetric techniques, in order to compare them, and measure the degree of precision of the execution of the façade. This paper describes the tracings, analysing in detail the ones for the coronation, the pediment and the niche of Saint Clare in the entrance façade and the rere-arch in the vestibule of the convent. The existence of different tracings for some elements, ranging from crude drafts to precise drawings, challenges a widespread assumption: it seems that the function of these tracings was not limited to the execution phase, and in some cases they served as design sketches for the project. Finally, the authors make some remarks about the research opportunities and conservation challenges posed by these material sources of construction history. Keywords Stonecutting, full-scale tracings, eighteenth-century architecture, Santiago de Compostela, Simón Rodríguez, project drawings, execution drawings Introduction From Antiquity to the Baroque Age, at least, builders have used full-scale tracings in order to guarantee the formal control of the members they were executing. 1 It is quite easy to surmise that these tracings were translations of reduced scale drawings in papyrus, parchment or paper, but the scant documentary evidence does not point this way. For example, the well-known Vitruvian passage on ichnography, that is, plans or horizontal projections, mentions explicitly that such drawings were prepared in solis arearum, the area where the future building is to be placed, with no mention to reduced-scale drawings. 2 Later on, in the Spanish Renaissance, Hernán Ruiz did not understand the concept of area and mistook it for a tracing floor or specialised flatbed where tracings are made “with ruler and compass and square”. Since there is no reference to reduced-scale drawings, again, we may surmise that these instruments were 81 José Calvo-López, Miguel Taín-Guzmán and Idoia Camiruaga-Osés