Jastres-nord, Archaeological site in Lussas, France.

Jastres-Nord, also called La grande muraille, is a Gallo-Roman oppidum on a spur of the Jastres plateau in Lussas, Ardèche, at 290–320 m elevation. Its 7-hectare area is enclosed by a stone rampart, the most visible remain: low, ruined walls of small pale grey and tan blocks with visible mortar, curving across the ground. The wall has seven towers, alternately round and square, and in its last state was 6 m thick.

A dry-stone rampart enclosing 4 hectares was built around 130 BC. In the second third of the first century BC a new wall with five towers, a bent entrance and a bastion was added to the south. At the end of the first century BC it was rebuilt and extended, reaching 6 metres in thickness, before the site was abandoned when Alba became the Helvian capital.

The site is also called La grande muraille, the great wall. Excavations of the main gate in the 1970s–1990s yielded over 160 metal objects, mostly from the burning of the monumental wooden door that gave access to the settlement. The oppidum may have been the capital of the Helvii before their town moved to Alba-la-Romaine.

The ruins can be visited and offer a good view of ancient building techniques and fortification structures. It is best to wear sturdy shoes, as the terrain is uneven and not all paths are paved.

During excavations, 160 metal objects were found that show there was once a large wooden gate here. This gate was so valuable and well-guarded that it was later destroyed in a fire.