The Benedictine abbey of Saint-Hilaire was built on the site of the chapel built at the request of Saint-Hilaire, first bishop of Carcassonne, in the 6th century, which was buried in its oratory. In the 8th century, this chapel was replaced by a church built by the founding monks of the abbey.
The abbey was initially placed under the name Saint-Saturnin, or Saint-Sernin, the first bishop of Toulouse. The abbey passed under the patronage of Saint-Hilaire during the discovery of the sacred remains of his body made in the abbey church on 22 February 970, at the request of Roger I, Earl of Carcassonne and his wife Adelaide. They took the rule of Saint Benedict, became the great benefactors of the abbey and were buried about 1012, in the sanctuary of the abbey church.
From the 11th to the 13th centuries, the abbey gained considerable importance and influence throughout the region.
The monastery of Saint-Hilaire was devastated by the Crusaders, which led to the restoration work carried out by Guillaume, abbot from 1237 to 1260. The cloister was built under the abbey of Bertrand de Touron (1323-1340).
The second half of the fourteenth century experienced the devastation caused by the epidemic of the Black Death and great insecurity during the Hundred Years War. The monastery developed and maintained its fortifications, resulting in additional expenses. In 1741, the property of the abbey was alienated or possessed by private individuals. There were only seven religious left. In 1748, the Bishop of Carcassonne enacted a decree for the extinction and suppression of the claustral offices and monastic squares of the abbey of Saint-Hilaire.
The abbey church became the parish church in 1758. The current bell tower was erected in 1898.

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It should be noted that the "Blanquette de Limoux" was invented in 1531 by the monks of the abbey of Saint-Hilaire. It is the oldest effervescent wine in the world.

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Source here.