A small monastery was founded in Altomünster by Saint Alto, a wandering monk, in about 750. The vita of Alto, likely written by Otloh of St. Emmeram after 1056 and ostensibly based on oral knowledge (written lore having been lost through plunder), reports that the monastery was visited by Saint Boniface, who dedicated the church. Another 11th-century text notes that Boniface also dedicated the church in nearby Benediktbeuern Abbey.
Sometime before 1000 the Welfs enlarged it and made it into a Benedictine abbey. Welf I, Duke of Bavaria resettled the monks in 1056 to the newly founded Weingarten Abbey in Altdorf, while the nuns formerly resident at Altdorf moved to Altomünster, where they lived until the monastery was dissolved in 1488 by Pope Innocent VIII.
In 1496 by grant of Duke George the Rich the Bridgettines of Maihingen were permitted to establish a Bridgettine monastery at Altomünster. The monastery was dissolved on 18 March 1803 during the secularisation of Bavaria, but was later revived. Today, along with a settlement in Bremen, it is the last Bridgettine monastery in Germany. Nearby is a museum of the history of the Bridgettine Order.
Two gospel lectionary created for the abbey in the 12th century are held by the Bavarian State Library.References:
The Abbey of Saint-Etienne, also known as Abbaye aux Hommes ('Men"s Abbey'), is a former monastery dedicated to Saint Stephen (Saint Étienne). It is considered, along with the neighbouring Abbaye aux Dames ('Ladies" Abbey'), to be one of the most notable Romanesque buildings in Normandy. Like all the major abbeys in Normandy, it was Benedictine.
Lanfranc, before being an Archbishop of Canterbury, was abbot of Saint-Etienne. Built in Caen stone during the 11th century, the two semi-completed churches stood for many decades in competition. An important feature added to both churches in about 1120 was the ribbed vault, used for the first time in France. The two abbey churches are considered forerunners of the Gothic architecture. The original Romanesque apse was replaced in 1166 by an early Gothic chevet, complete with rosette windows and flying buttresses. Nine towers and spires were added in the 13th century. The interior vaulting shows a similar progression, beginning with early sexpartite vaulting (using circular ribs) in the nave and progressing to quadipartite vaults (using pointed ribs) in the sanctuary.
The two monasteries were finally donated by William the Conqueror and his wife, Matilda of Flanders, as penalty for their marriage against the Pope"s ruling. William was buried here; Matilda was buried in the Abbaye aux Dames. Unfortunately William"s original tombstone of black marble, the same kind as Matilda"s in the Abbaye aux Dames, was destroyed by the Calvinist iconoclasts in the 16th century and his bones scattered.
As a consequence of the Wars of Religion, the high lantern tower in the middle of the church collapsed and was never rebuilt. The Benedictine abbey was suppressed during the French Revolution and the abbey church became a parish church. From 1804 to 1961, the abbey buildings accommodated a prestigious high school, the Lycée Malherbe. During the Normandy Landings in 1944, inhabitants of Caen found refuge in the church; on the rooftop there was a red cross, made with blood on a sheet, to show that it was a hospital (to avoid bombings).