The Twenty-Seven Kilometre Dry-Stone Wall the French Built Across the Provençal Hills to Contain a Single City's Plague

The Mur de la peste (‘Plague Wall’) was a continuous dry-stone wall approximately 27 km long, approximately 1.8 metres tall, with substantial guard posts at 100-metre intervals, built across the limestone garrigue of the Comtat Venaissin between Cabrières-d’Avignon and Méthamis. It was constructed between September 1720 and August 1721 by approximately 1,000 conscripted Comtat labourers under the joint authority of the French royal regency and the papal Comtat administration. Its purpose was the enforcement of the cordon sanitaire that contained the Great Plague of Marseille within Provence.

Why a wall

The standard 18th-century European plague-response framework was the cordon sanitaire — a military line that prohibited movement across a quarantine boundary. The Provençal cordon of 1720 had been declared by the regency in September 1720, but enforcement through a thinly-populated rural landscape of Mediterranean garrigue was practically impossible without a physical barrier. The garrigue offered too many small paths for fleeing refugees to slip through; the regency’s available troops were too few to picket the entire boundary continuously.

The wall provided the physical baseline. Guards at the 100-metre interval posts could intercept anyone attempting to cross; the dry-stone construction was tall enough to require deliberate climbing; the substantial visible presence functioned as deterrent as much as physical barrier.

What it cost

Construction was substantially fast. The dry-stone technique required no mortar or specialised skill; local Provençal masonry traditions had been building boundary walls of similar form for centuries. The 1,000 conscripted labourers worked in approximately 100-metre sections; the entire 27 km length was operational within eleven months. Total cost is estimated at approximately 35,000 livres — a but manageable expenditure given the alternative (further spread of plague into the Rhône valley and Lyon).

The northern Comtat Venaissin border was also fortified but with conventional military picketing rather than a wall; the wall itself covered only the most exposed section between Cabrières-d’Avignon and Méthamis, where the geography required physical barrier.

What it accomplished

The cordon held. The plague did not escape Provence. The Languedoc, Dauphiné, and Lyonnais — directly adjacent to the affected region — had no significant outbreak. The wall’s success became the standard European model for plague containment and influenced subsequent disease-control architecture through the 19th century.

The wall was abandoned at the end of the outbreak in 1722. Local farmers used the stones as building material through the next two centuries. Approximately 6 km of intact wall and several restored guard posts survive in the Parc naturel régional du Luberon and are open to public visitors.