| Summary: | The remains from the forum of Bavay (Nord) demonstrate the use of terracotta, bricks and tiles. Here, we attempt to characterize those remains, determine their origin and quantity, as well as their role in the economy and the construction of the site.The forum is among the largest in the provinces of the Empire, and it is also one of the rare sites to be almost entirely unearthed by excavations that began at the beginning of the 20th c. and are still ongoing today. It measures 240 by 110 m and is divided into three parts: the sacred area to the west, a central esplanade and a basilical area to the east. Apart from the souterrain parts of the cryptoporticus, the conservation status of the elevations is poor; they only reach heights of 1 to 2 m in certain sectors. However, a hypothesis of reconstruction with a model of architectural information was initiated during a mediation project (Cyberforum) and updated in the scope of this article.The forum underwent two main phases, which extended over the same surface, but present several differences; the detailed layout of the areas, elevations, and especially construction techniques; the second phase introduced the use of levelling courses of bricks in low walls. These constructions are not homogeneous and must therefore be characterized on the basis of the different techniques used in each of the preserved sectors in order to envisage the rendering of the lost elevations. Depending on the structures, the walls contain two or three rows of bricks for three, five, seven to twelve courses of rubble. As a result, it is possible to quantify the volumes of masonry in general and in particular, of architectural terracotta.The terracotta materials used at Bavay include covering tiles (tegula and imbrex) and square and rectangular bricks; where the latter are more abundant with rather irregular metrology. The bricks present artisans’ trademarks; 437 specimens were recorded for 35 types, with ATAB, ATIL, CVS, FAL, HAMSIT or TRPS being the most frequent. All these artisans worked in the Meuse Valley between Hastière and Hermalle-sous-Huy (Belgium), the only two known workshops, but an in-depth geological study demonstrated the homogeneity of the supply source. The study of the terracotta also allowed to discuss the dating of the construction of the second forum. An archaeomagnetic analysis estimated the firing period between 190 and 230 AD, which is in keeping with the date on a Commode coin (192 AD) and an important batch of terra sigillata, proposing 185 AD as a terminus post quem.After the architectural study and the digital rendering of the elevations, it was furthermore possible to estimate the volume of masonry at nearly 20,000 m3 and the roof surface at 8,000 m2. The characterization of the materials in terracotta and their incorporation in the different walls enabled us to estimate a volume of between 2,000 and 2,750 m3 (3,600-4,950 t) and a volume of tiles of 246 m3 (440 t).The supply of terracotta from a relatively distant region raises questions, as there were nearer workshops in activity. On account of the considerable quantity of terracotta required, multiple suppliers were called upon, spread over the Meuse Valley, which led to a relative heterogeneity of materials, but reduced waiting time in line with the needs of the site. In addition, the Meuse workshops could avail of good communication routes as the Sambre, the main tributary of the Meuse, links Namur to Pont, where an agglomeration must have acted as a port for the town located less than 10 km away.Once the terracotta arrived on the construction site of Bavay, it had to be used in the colossal building project. In the same way as J. DeLaine, we consulted engineering works from the 19th c., in which the techniques described are similar to those used in the pre-industrial economy, but with modern rationalisation. This approach enables us to evaluate the number of hours of work required although the workforce whose importance and skills remains unknown. In any case, judging by the example of the thermal baths of Trajan in Rome, and therefore subject to the available finances, only one season could allow the completion of the structural work.In addition to these results relative to the history of a monument, this article attempts to apply a precise analytic approach to the constructions and the materials used to build them. Starting from an in-depth observation of the remains, and a comparison with the standards of Roman architecture enable us to present an architectural proposal; From the analysis of the materials, an origin and supply circuits are defined; in the end, their combination serves an economic discourse that similar studies will be able to refine.
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