Ancienne abbaye bénédictine Saint-Grégoire, Benedictine monastery in Munster, France.

The former Benedictine Abbey of Saint Gregory is a partially destroyed complex featuring 17th-century vaulted cloisters and a spiral staircase leading to the former monks' cells. The remaining structures still show the architectural order of the monastery with its distinctive vaults and passages.

The monastery was founded around 660 at the confluence of the Petite Fecht and Grande Fecht, possibly after an earlier monastic settlement in the valley around 633. Childeric II made a major donation in 675, and Louis the Pious granted privileges in 823; in 1235 the abbey gained judicial lordship over the Gregoriental and became a Reichsabtei. It was dissolved in 1791 during the French Revolution.

The abbey's name Munster derives from Monasterium, the Latin word for monastery, and gave the town its name. In 1575 the community signed the Kientzheim agreement, confirming residents' freedom of worship and obliging it to pay the pastor of Munster. Its library of manuscripts was prized in the 18th century and was taken over by Colmar after 1790.

The abbey ruins stand in the centre of Munster, near the confluence of the Petite and Grande Fecht. The site is inscribed as a monument historique since 25 May 1990 and was largely abandoned from the 1990s until a valorisation project began in the early 2020s. Only the abbatial lodging and some cloister ruins remain, so expect partial structures rather than a complete complex.

The abbey library was still prized in the 18th century for its manuscripts, which the city of Colmar took over after 1790. The monastic buildings were rebuilt between 1682 and 1686, while the abbot's palace was only finished between 1786 and 1789, shortly before the abbey was dissolved in 1791.