The so-called «ville basse » of Castellas, in Murviel-lès-Montpellier (Hérault), covers the slopes of a hill on the top of which stands an oldest settlement – «ville haute » -that existed at least in the IInd century BC. The powerful fortification walls made of large stones that surround the «ville basse » adjoin the wall of the upper village at one end and, at the other end, lean against a retaining wall which separates upper and lower cities. Excavations lead between 2001 and 2008 in the vicinity of the walls and of the gates place the erection of the fortifications around the middle and/ or during the third quarter of the Ist c. BC. The nature and evolution of these peripherical zones have been characterized when digging and their chrono...