Saint-Sever-Calvados Abbey was founded by Guillaume Sanche, the lord of Gascony in the late 10th century. According to the monastic chronicles, this was as the result of a vow he made after the battle of Taller, in Gascony, in which he defeated the Vikings (982). In 1060, after a fire, the abbey was reconstructed on the model of Cluny under the direction of the abbot Gregori de Montaner. The Saint-Sever Beatus was the work of monks working under the direction of the same abbot; Abbot Gregori held the post from 1028 to 1072.
Today there is a Gothic abbey church and a bell-tower on opposite sides of the square. There were centuries when people built, and others when they did not hesitate to split a building in two. The choir was a Benedictine enclosure, with the other half open to the people. However, except for the tower, this second half of the church has not been survived. The French Revolution drove the monks away and the abbey was closed.References:
The Basilica of Santa Maria in Trastevere is one of the oldest churches of Rome. The basic floor plan and wall structure of the church date back to the 340s, and much of the structure to 1140-43. The first sanctuary was built in 221 and 227 by Pope Callixtus I and later completed by Pope Julius I.
The inscription on the episcopal throne states that this is the first church in Rome dedicated to Mary, mother of Jesus, although some claim that privilege belongs to the Basilica di Santa Maria Maggiore. A Christian house-church was founded here about 220 by Pope Saint Callixtus I (217-222) on the site of the Taberna meritoria, a refuge for retired soldiers. The area was made available for Christian use by Emperor Alexander Severus when he settled a dispute between the Christians and tavern-keepers.
The church underwent two restorations in the fifth and eighth centuries and in 1140-43 it was re-erected on its old foundations under Pope Innocent II.