The abbey of Saint-Michel-de-Cuxa (Catalan: Sant Miquel de Cuixà) is a Benedictine abbey located in the territory of the commune of Codalet, in the Pyrénées-Orientales département, in southwestern France. It was an important cultural centre in the regency of Abbot Oliba.
Parts of it now makes up the Cloisters museum in New York City.
The origins of Cuixà abbey lie at Sant Andreu d’Eixalada, an abbey founded by the Benedictines in about 840, and located at the head of the Tet valley. In the autumn of 878, the river broke its banks, flooding and destroying the monastery (located near the river-bed) forcing the monks to seek refuge in the surrounding countryside. The community then transferred to Cuixà, a minor cenobitic community dedicated to Saint Germanus, led by Father Protasius.
In June 879, Protasius and Miro the Elder, count of Conflent and Roussillon, signed the founding treaty of the new monastery, whereby Cuixà extended its properties with those contributed by Eixalada and Protasius was named abbot.
The abbey continued under the protection of the count of Cerdanya and Conflent. The territory then came under the domain of the family of Wilfred I, count of Barcelona in 870. In about 940, under the initiative of Sunifred II of Cerdanya, a new church dedicated to Saint Michael was built. In 956 the building was refurbished and made more sumptuous; the main altar was consecrated on 30 September 974 by Garí, a monk from Cluny who led five southern monasteries.
When the Doge of Venice, Pietro I Orseolo, accepted Romuald's advice to become a monk, abdicated his office, and fled in the night, it was to Saint-Michel-de-Cuxa that he retired, accompanied by Romuald and his companion, Marinus, who established a hermitage nearby.
Although he probably never came there, Cesare Borgia was named by his father as abbot of Saint-Michel-de-Cuxa in 1494, among many other titles earning him revenues, and remained so until 1498.
The Abbey was nationalised along with other ecclesiastical properties throughout France in the French Revolution. In 1790 the last monks were evicted and the Abbey was sold. Subsequently, the buildings fell into disrepair.
Some sculpture from the Abbey found its way into a collection of George Grey Barnard (1863–1938), a prominent American sculptor, and an avid collector and dealer of medieval art. In 1914, Barnard opened his "Cloisters" exhibit on Fort Washington Avenue, New York, along with sculpture from a number of medieval sites. The Cloisters was rebuilt and expanded by John D. Rockefeller, Jr. in 1938 at Fort Tryon Park, Upper Manhattan and is now a significant Medieval museum within the Metropolitan Museum of Art. The centerpiece and namesake of the museum is a cloister built using fragments of the 12th century cloister of Saint-Michel-de-Cuxha 
The Cuxa Abbey was refounded at its original site under the Cistercians, a reformed version of the Benedictines, in 1919.
The famous cellist, Pablo Casals, was filmed in the abbey in 1954 as he performed Bach's Suite No. 1 in G Major.
The Abbey was transferred back to the Benedictines proper in 1965.