The Gier Aqueduct runs for 12km solely across the commune of Saint-Chamond, between the water-source above Moulin Combat and its departure towards l’Horme near Chapelle du Fay.
Over 30 sites have been identified in the commune, mostly at the time of the construction of a motorway bypass, which destroyed a certain number of them.
It was found notably under the former Izieux dye-works, where it had been used as a passage for industrial pipelines.
It was also seen at the Varizelle shopping centre (Leclerc, Leroy Merlin, Gamm vert), where a maintenance shaft was brought to light during preventive excavations.
The Aqueduct crosses the communes of L’Horme, La Grand’Croix, Lorette, Cellieu, Saint-Romain-en-Jarez, and Valfleury before arriving at Chagnon.