In 1009 Herswithehusen (Hardehausen) became the property of Meinwerk, bishop of Paderborn. The abbey was founded in 1140 by bishop Bernhard I of Paderborn as a daughter house of Kamp Abbey on the Lower Rhine. Construction was completed with the dedication of the church in 1165.
During the Thirty Years' War the abbey was looted and destroyed. During its reconstruction in the years 1680 to 1750 it received its present form.
In 1803 the abbey was secularised, and the monks expelled. The contents were sold or auctioned, and the church was demolished in 1812. The estates were rented out as state property.
Hardehausen was briefly re-founded as a Cistercian monastery in 1927, but the new community was brought to an end by an order of dissolution issued by the National Socialist government in 1938, when the buildings and grounds were sold to the Henschel company from Kassel, from whom they were acquired by the Verein für katholische Arbeiterkolonien ('Union for Catholic Workers' Colonies'). In 1944 the Nationalpolitische Erziehungsanstalt (Napola) Bensberg transferred to Hardehausen. At this period an external work party from Buchenwald concentration camp, consisting of 30 prisoners, were deployed for forced labour in Hardehausen.
Since 1945 the former monastery has been used for the educational activities of the present Archdiocese of Paderborn. In 1970 all the buildings on the site were altered and extended for their educational functions.
References:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.