The church of Saint-Pierre de Marnans is located in a secondary valley between Lyon and Valence. It belonged to a monastic establishment active between the 12th and 16th centuries, first occupied by a community of canons regular and later by Antonines. Of the former monastery, only its remarkable Romanesque church has survived.
The earliest known reference to Saint-Pierre de Marnans dates to around 1070, when the church, then parochial, was donated to the Abbey of Saint-André-le-Bas of Vienne (Isère), during the time of Archbishop Leodegarius (1030–1070). The donation was made by the widow Élisabeth and her five sons. The church is mentioned again in a document from Pope Adrian IV, dated 1157, confirming property in favour of the archbishopric of Vienne, without any reference at that time to monastic functions.
Its status as a cenobitic establishment is confirmed in 1164, in a donation of land made by the Archbishop of Vienne. The nature of the community occupying the site at that time is unknown: it has been suggested that it may have been Benedictine, owing to the connection with Saint-André-le-Bas, or else canons regular, who are attested there in the last quarter of the 12th century. It may then have been dependent on the Abbey of Saint-Barnard de Romans (Drôme). It was also during this period that the church preserved today was probably built.
A century later, Marnans was in clear decline and, for this reason, in 1286 the archbishop requested that the priory — without specifying on which monastery it depended — be placed under the protection of a house capable of ensuring its survival. The situation was resolved in 1287 with its attachment to the Abbey of Saint-Antoine (Isère), which was then enjoying a period of prosperity. From that point on, Marnans became an Antonine house, dependent on the abbot of Saint-Antoine, who delegated its administration to a prior or commander resident at the site.
This new arrangement led to an economic revival of the priory, which lasted until around 1562, when the site was devastated during the Wars of Religion. The priory lost its cloister and other buildings, and only the church survived, despite attempts to blow it up. Marnans probably lost its community at that time, but the church was able to resume its parochial functions and remained linked to Saint-Antoine until the Order of the Hospital of Saint John of Jerusalem (Order of Malta) took charge of the site after the suppression of the Antonines.
Today, only the former priory church survives, now serving as a parish church, together with a few remains of the vanished monastic buildings. It is a single-nave structure of four bays, terminated by an apse, with a transept provided with two apsidioles opening onto its arms. The western portal and the capitals of the nave are also noteworthy. The building can be dated, for the most part, to the last quarter of the 12th century.
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- COLARDELLE, Michel i altres (1983). Le prieuré de Marnans. Histoire et archéologie. Archéologie médiévale. Vol. 13
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- GOUBET, Simone (1974). Église de Saint-Pierre de Marnans. Congrès archéologique de France, 130 ss. Société française d'archéologie
- LAGIER, A. (1901). Notice sur l'église de Saint-Pierre de Marnans. Annales Dauphinoises, Vol. II. Grenoble: Vallier
- MAILLER-GUY, Luc (1909). Les paroisses antoniennes de l'ancien diocèse de Vienne. Bulletin de l'Académie delphinale. Grenoble: Allier
Marnans (Isère) lies to the south-east of Vienne in the Dauphiné, between that city and Grenoble