Abstract Based on the concept of “material ecology”, which designates the structural properties of space and objects in the constitution of places of scientific practice, this article proposes a socio-historical analysis of the materiality of Toulouse observatories in the 18th century. Toulouse observatories reveal the importance of the material dimension in the organization of scientific work throughout the 18th century. First, the article demonstrates how the material infrastructure of the observatory of the short-lived Academy of Sciences of Toulouse contributed to creating and consolidating the local astronomical community. Secondly, it shows that the architectural characteristics of the observatories built by the most active astronomers in Toulouse served as a model to design later scholarly institutions. The patrimonialization of the old observatories at the beginning of the 19th century is finally discussed. By resorting to the notion of material ecology concerning the places of astronomical observation, the article brings to light the socio-epistemic dimension that underpins scientific practice.