Yes / Two seasons of geophysical prospection (magnetic, resistance and ground-penetrating radar) were conducted at the Iron Age oppidum of Le Castellan, Istres, Bouches-du-Rhône, in order to determine the utility of these techniques for sites in this region. The survey revealed numerous strong anomalies, of which many ran parallel or perpendicular to one another. These are the sorts of responses one might expect from the remains of buried stone wall foundations; this interpretation is supported by the presence, on the west side of the site, of exposed walls on the same alignment as certain of the geophysical anomalies. Overall, the evidence suggests a network of buried buildings and road-ways across the oppidum. One particularly substantial building was identified towards the centre of the site, through the presence of a strong resistance anomaly of distinctly rectilinear form. It appears to represent the remains of a buried stone building with three rooms. In conclusion, the results provide strong encouragement for the further application of geophysical survey in this region