Nonneseter Abbey is first recorded by name in 1262, but certainly founded many years earlier, possibly in or about 1150. It was dedicated to the Virgin Mary. The nuns apparently belonged to the Cistercian Order, although this is not confirmed until as late as 1494. It seems probable that a hospital run by the nuns, documented in 1411, was the forerunner of the later St. George's (Sankt Jørgens) lepers' hospital.
In 1507 the nuns were ejected for immoral and unseemly behavior and the buildings were transferred to the Hospital Brothers of St. Anthony, but the monastery was secularized in 1528, and the premises were converted into a private fortified residence, under the name of Lungegården, by the new proprietor, Vincens Lunge.
The surviving buildings were mostly destroyed by a fire in 1891, and of the monastic buildings there remains nothing to be seen. Of the abbey church there survived the base of the west tower, and the Nonneseter Chapel, originally the south chapel off the choir, which were acquired in 1891 after the fire by the Society for the Preservation of Ancient Norwegian Monuments.
The single story that is left of the west tower, the Tårnfoten ('tower foot'), is near the present Bergen public library, and measures 8.6 meters square. It was originally clad with dressed stone. In the west wall is a portal with a round arch, and in the east wall another, which would have connected to the body of the church. It is now used as a memorial chapel to the fallen of World War II.
The Romanesque tower foot is more old-fashioned in style than the body of the main church apparently was, indicating the possibility that it could have belonged to an older structure predating the arrival of the Cistercians with their characteristic building style.
The church lay to the east of the tower. The original building was quite small, but it seems to have been extended eastwards in the later 13th century with a new choir and choir chapels; it had a single aisle. The graveyard was to the north of the church, and the monastic buildings to the south, but there are too few remains of them to establish the exact layout.
The Nonneseter Chapel (Nonneseter kapell) at Kaigaten 3 is believed to have been one of the choir chapels. It measures about 8 meters by 7 meters, and contains a vaulted ceiling and Gothic arched windows. It dates from around 1250, which seems to be when the church was extended. Between 1951 and 1989 it was used as a church for deaf people. It is now used, among other ways, as a concert hall.References:
Steinvikholm Castle is an island fortress built between 1525 to 1532 by Norway's last Catholic archbishop, Olav Engelbrektsson. Steinvikholm castle became the most powerful fortification by the time it was built, and it is the largest construction raised in the Norwegian Middle Ages.
The castle occupies about half of the land on the rocky island. The absence of a spring meant that fresh water had to be brought from the mainland. A wooden bridge served as the only way to the island other than boat. Although the castle design was common across Europe in 1525, its medieval design was becoming obsolete because of the improved siege firepower offered by gunpowder and cannons.
The castle was constructed after Olav Engelbrektsson returned from a meeting with the Pope in Rome, presumably in anticipation of impending military-religious conflict. As Archbishop Engelbrektsson's resistance to the encroachment of Danish rule escalated, first with Frederick I of Denmark and his successor Christian III of Denmark, Steinvikholm Castle and Nidarholm Abbey became the Catholic Church's military strongholds in Norway. In April 1537, the Danish-Norwegian Reformation succeeded in driving the archbishop from the castle into exile in Lier in the Netherlands (now in Belgium), where he died on 7 February 1538. At the castle the archbishop left behind St. Olav's shrine and other treasures from Nidaros Cathedral (Trondheim). The original coffin containing St. Olav's body remained at Steinvikholm until it was returned to Nidaros Cathedral in 1564. Since 1568 St. Olav's grave in Nidaros has been unknown.
From the 17th to 19th century, the island was used as a quarry and some of its masonry was sold and removed from the site. This activity was condoned by the Danish-Norwegian authorities as a way of eliminating a monument to the opposition of the Danish–Norwegian Union.
Steinvikholm fort is owned and operated today by The society for the Preservation of Norwegian Ancient Monuments. The island has been the site of the midnight opera which details the life and struggles of the archbishop. The opera is held in August annually. The opera is organized by Steinvikholm Musikkteater since the beginning in 1993.