Grestain Abbey (Abbaye Notre-Dame de Grestain) was an 11th century Benedictine monastery. Closely associated with the family of William, Duke of Normandy, the abbey was instrumental in the Normans taking control over the Catholic Church in England in the centuries following the Norman Conquest of England, establishing new churches and priories in England, and Abbots of Grestain ordained many English priests. Many churches mentioned in the Domesday Book cite Grestain as the founding establishment.
The Abbey was founded in 1050 by Herluin de Conteville and his wife Arlette, mother of William the Conqueror. Herluin, a victim of leprosy, was said to have seen a vision of the Blessed Virgin Mary who told him to take a spa treatment at the source of the Carbec stream in Grestain (Carbec meaning 'the Stream of Kari'). Cured, he decided to build an abbey in the nearby Valley of Vilaine dedicated to the Virgin and a chapel at Carbec, a site also dedicated to the healing spring of Saint-Méen. Herluin's son, Robert de Mortain, half-brother of William, was the principal benefactor, endowing it with his revenues from England.
In 1358, the abbey was sacked by the Anglo-Navarrais. The monks took refuge at their safe house in Rouen, in the parish of Saint-Eloi. Between 1364-1365 the abbey was attacked once more. On the return of the monks, the abbey had been partly destroyed and nearly rased to the ground.
The abbey was officially closed in 1757 on the orders of the bishop. The church buildings were demolished around 1766 and the rest of abbey destroyed in 1790; of these buildings, only a few ruins remain, integrated into the Château de La Pommeraye (a private property): a defensive wall, a 13th-Century portal, an 18th century manor with a 13th century floor, and remains of the church.A monunment has been erected to the memory of the founders who were buried in the now defunct church: Arlette, Herluin and Robert de Mortain, as well as Robert's wife, Mathilde de Montgomerie, daughter of Roger de Montgomerie.References:
First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.