The Convent of Saint John is an ancient Benedictine monastery in Müstair village of Val Müstair, Switzerland, and, by reason of its exceptionally well-preserved heritage of Carolingian art, has been a UNESCO World Heritage Site since 1983.
It is believed that the abbey was established ca. 780 by a bishop of Chur, perhaps under orders from Charlemagne. It was built during a wave of monastery construction that included the nearby monasteries at Cazis, Mistail, Pfäfers, and Disentis. The abbey was located along the Val Müstairpass over the Alps from Italy and was fortified to allow it to control the pass. In 881 the abbey passed over to be completely under the control of the Bishop of Chur. During the early years of the abbey, in the early 9th century, a series of frescos were painted in the church. Later, in the 11th and 12th centuries, the abbey experienced a second expansion and new paintings were added or painted over the old frescos. These paintings were lost and were only rediscovered in the 20th century.
In the 10th century, the church tower was added to the abbey church. During the expansion of the 11th century the bishop of Chur enlarged his residence at the monastery. A fine tower home, cloister, and the double chapel of St. Ulrich and St. Niklaus were added. During the expansion, the two-story residence chapel of the bishop was also decorated with extensive stucco and fresco work. At some time in the 12th century it was converted from a monastery into a convent. The change to a nunnery is first mentioned in 1167, but it happened sometime before this date.
The Swabian War, which was an attempt by the Habsburgs to assert control over the Grisons and key alpine passes, started at the convent. On January 20, 1499, Habsburg troops occupied the surrounding valley and plundered the convent, but were soon driven back by the forces of the Three Leagues at the Battle of Calven. Following the raid, an armistice was signed between the Habsburgs and the Three Leagues. However this armistice only lasted a few days before the conflicts broke out between the Three Leagues' Old Swiss Confederacy allies and the Habsburg troops. These raids quickly escalated into the Swabian War, which ended in September 1499 with the Treaty of Basel granting virtual independence to the Swiss Confederacy.
About 1500 the convent church was modified from a single-nave Carolingian construction into a three-nave late gothic church. Shortly there after, in 1524 and 1526, the Ilanzer Articles weakened the temporal power of the bishop of Chur and reduced the financial support of the convent. There was limited construction on the convent following this reduction in income.
In the spirit of the Council of Trent the bishop issued a series of reforms governing religious life from 1600 to 1614. The reforms included who could receive sacraments and created a new Breviary. Other policies, such as the requirement for common sleeping areas, were also relaxed in this era.
Throughout the history of the Convent of Saint John there were conflicts between the bishop of Chur, the Grey League, and the House of Habsburg. The Convent's spiritual leader, the abbess, and the physical leader, the vogt, were often chosen by one of these three powers.
During the 20th-century restoration works, some Romanesque frescoes from the 1160s were discovered here. Other murals are dated to Charlemagne's reign. The UNESCO recognized these as "Switzerland's greatest series of figurative murals, painted c. A.D. 800, along with Romanesque frescoes and stuccoes".
The original single nave church with five apses has several significant Early Middle Ages frescoes from around 800. The paintings are organized in five rows that stretch from the southern wall across the west wall to the northern wall. The top row features scenes from the life of King David of the Hebrew Bible/Old Testament. The next three rows show scenes from the youth, life, and Passion of Christ. The bottom row contains scenes from the crucifixion of St. Andreas. On the western wall the rows are tied together with an image of the Last Judgment. The paintings were done in a limited range of colors including ochre, red, and brown and help in the "comprehension of the evolution of certain Christian iconographic themes, like that of the last judgment".
The apses and the eastern wall were repainted in the 12th century with Romanesque frecsos showing a variety of biblical themes including the dinner of Herod Antipas (where the dancing of Herodias' daughter leads to the execution of John the Baptist), the wise and foolish virgins, apostles, and St. Stephen.