The Saint-Pierre Abbey in Airvault was initially a collegiate church of regular canons of Saint Augustine, founded around 990 by Audéarde, wife of Viscount Herbert I of Thouars. As the canons were lax in following the rules of the Order of Saint Augustine, the Bishop of Poitiers decided to send a monk from the Augustinian abbey of Lesterps in Limousin to reform it. Pierre de Fonte Salubri (of Saine Fontaine) was appointed the first abbot of Airvault in 1096 and died on August 7, 1110. He undertook the construction of the abbey church. According to the Chronicle of Saint-Maixent, the church was consecrated in 1100 but subsequently underwent modifications and additions.
After the creation of the diocese of Maillezais in 1317, transferred to La Rochelle in 1648, the abbey became dependent on it.
During the Revolution a road was pierced through the abbey separating the convent buildings of the abbey. Several buildings are still visible as the room called the 'vat', the 'prison' (fortified gate), underground rooms, the fourteenth-century chapel and especially the abbey house which has hosted since 1975 the municipal museum.
Towering 52 meters above the sea, Bengtskär lighthouse is the tallest one in Scandinavia. The building started in in 1905 after the shipwreck of S/S Helsingfors and was completed in 1906. The lighthouse was designed by architect Florentin Granholm. On December a special petrol lantern, designed and built in Paris, was brought to Bengtskär and installed atop the tower.
German fleet bombarded Bengstkär in the First World War in 1914. Since the Gulf of Finland was heavily mined, it was not until 1919 that the surrounding seas were declared safe for shipping, that the light was lit again.
After the war the military value of Bengtskär increased as part of the defence system of independent Finland. In Second World War (1941) Soviet Union made a suprise attack to island. After a bloody battle, the small Finnish garrison emerged victorious. Intermittent repairs to the facility continued during the post-war period.