Abbaye Saint-Jean-du-Mont de Thérouanne, Benedictine abbey in Thérouanne, France

Abbaye Saint-Jean-du-Mont de Thérouanne is a ruined Benedictine monastery in the French village of Thérouanne, with remains scattered across undulating terrain. Stone foundations and wall fragments reveal the layout of what was once a substantial monastic complex.

The abbey was founded in 686 by Thierry III, king of the Franks of Neustria, as expiation for the murder of Saint Léger. In 1553 Charles V destroyed Thérouanne, and the monks fled, first to Bailleul, then to Ypres, where the community settled in 1598. It was suppressed under French rule on 2 November 1796, and the last fourteen monks were expelled on 23 January 1797.

The abbey was also known as Sint-Jan-ten-Berg or Saint-Jean d'Ypres, names that followed the monks after they left Thérouanne. Its abbot Jean Faschyn, who died in 1570, bore the motto "Corde et anima". The monastery held the patronage of the church of Reclinghem, and the monk Trivier of Thérouanne, who retired there to live a contemplative life, gave his name to two communes in the Ain.

The excavated foundations lie in a low mound; the higher courses stand on the left, while the centre and right are lower, with rubble and flat dark stones on pale gravel. A single dark upright slab marks the centre. Ground is uneven, so watch your footing.

The sources record no relic or pilgrimage tradition. What they do record is a turbulent end: after Charles V's troops destroyed Thérouanne, the monks fled, and the community was moved to Belle (1555-1598) and then Ypres (1598-1797). In 1716 and 1717 two fires, linked to abbot Alexandre-Louis de Gouy de Cartigny, destroyed the abbey library.