Foundation of the Priory 1061 (≈ 1061)
Created by Guy de Montlhéry and Hodierne de Gometz
XIVe–XVe siècles
Construction of barn
Construction of barn XIVe–XVe siècles (≈ 1550)
Dating by its architectural characteristics
Fin XVIIIe–début XIXe siècle
Expansion of the barn
Expansion of the barn Fin XVIIIe–début XIXe siècle (≈ 1925)
Demolition of the original West Wall
8 juin 2016
Site protection
Site protection 8 juin 2016 (≈ 2016)
Registration as Historic Monument
Aujourd'hui
Aujourd'hui
Aujourd'hui Aujourd'hui (≈ 2025)
Position de référence.
Heritage classified
In total, the old monastic barn; facades and roofs of the buildings of the old farmhouse; the floor of the courtyard including the "horse bath" basin; and the enclosure wall of the monastic agricultural complex (cf. AO 17, 18, 20): registration by order of 8 June 2016
Key figures
Guy de Montlhéry - Founder of the Priory
Co-founder with his wife in 1061
Hodierne de Gometz - Founder of the Priory
Wife of Guy de Montlhéry
Origin and history
The Clunisian Priory of Longpont was founded in 1061 by Guy de Montlhéry and Hodierne de Gometz, becoming a "regional network leader" thanks to its extensive land properties. This set justified the construction of a farm, a press and a monastic barn adjacent to the convent. The barn, remarkable for its high walls, imposing dimensions and structure, dates back to the 14th–15th centuries. It initially covered two thirds of its present surface, before being enlarged in the late eighteenth or early nineteenth century by the demolition of the west wall.
The site has retained its original environment, illustrating the central role of Clunisian monks in medieval society. The barn, the abbey church and the courtyard of the farm are among the rare remains of the priory. The set, protected since 2016, also includes the "horse bath" and the enclosure wall. These elements reflect the agricultural and spiritual organization of the estate, where architecture and landscape combine to witness eight centuries of history.
Ranked a Historical Monument, the monastic agricultural complex combines built heritage and collective memory. Its barn, one of the largest buildings of its kind in Île-de-France, symbolizes monks' ingenuity in land management. The basin and the preserved facades offer a rare overview of medieval agricultural techniques, while the location in Longpont-sur-Orge (Essonne) makes it a key site to understand the clunisian influence in the Paris region.