Le Cheslé

Le Cheslé is one of the most significant Iron Age archaeological sites in Belgium — a Celtic hilltop fortification rising above the village of Bérismenil, within the municipality of La Roche-en-Ardenne, in the province of Luxembourg. The site occupies a rocky promontory standing 80 meters above the Ourthe river valley and stretches across a plateau roughly 725 meters long and 290 meters wide, covering an area of about 13 hectares. It ranks as the second-largest known Celtic oppidum in Belgium, surpassed only by Tranchée des Portes in Étalle.

What kind of fortification was this?

The promontory on which Le Cheslé stands is naturally narrow, protected on one side by a steep slope falling toward the river and open on the other toward higher ground. It was precisely at this narrow neck that the Celts built the most critical part of their defenses: a rampart wall several meters high, constructed from earth, schist and timber. The full defensive system — a double rampart encircling the plateau — extended for more than 1,750 meters. The structure was expanded and reinforced repeatedly throughout the period of Celtic occupation, a sign of how long this place remained important to the surrounding population.

When was it built and what was it used for?

Archaeological research, carried out in part by the Université libre de Bruxelles, has focused especially on the barrier wall raised at the site's most vulnerable point — the narrow neck facing the open plateau, the direction from which an attack could come. Radiocarbon dating of recovered material places the earliest occupation of the site at around 519 BCE. Through the 7th, 6th and 5th centuries BCE, Le Cheslé served as a secure refuge for the population of nearby settlements — a place people could retreat to in times of danger, rather than a permanent dwelling site.

How was the site discovered?

The fortification was already marked on the Ferraris map in 1777, showing that its presence had long been known, even before its Celtic origin was recognized. The site's formal identification is credited to Sulbout in 1867. Since 1905, the area has been the subject of numerous excavation campaigns, which have gradually revealed the structure of the ramparts and yielded archaeological material that has deepened understanding of the people who once occupied this landscape.

What protected status does Le Cheslé hold today?

Given its historical and scientific value, Le Cheslé has been listed as a Patrimoine majeur de Wallonie (Major Heritage Site of Wallonia), under the name of the archaeological site of Cheslé and the Ourthe valley, covering the stretch between Maboge and Nisramont. This designation reflects the site's importance not only as an isolated oppidum, but as part of a wider cultural landscape along the river valley.

Frequently asked questions

Where exactly is Le Cheslé located? On a rocky promontory above the Ourthe river, near the village of Bérismenil, within the municipality of La Roche-en-Ardenne, in the Belgian province of Luxembourg.

How large is the site? The plateau occupied by the fortification measures about 725 meters long and 290 meters wide, with a surrounding rampart extending for more than 1,750 meters.

From what period does it date? Radiocarbon dating places the earliest occupation at around 519 BCE, with the site functioning mainly as a refuge between the 7th and 5th centuries BCE.

Can it be visited today? The site is a protected archaeological area listed as a Patrimoine majeur de Wallonie, reflecting its recognized historical value for the region.