Isen Abbey was a Benedictine abbey, later a collegiate foundation. Dedicated to Saint Zeno of Verona, the abbey was founded by members of the Fagana family, an indigenous Bavarian noble clan, and by Bishop Joseph of Freising (also known as Joseph of Verona) in the 8th century, about 752. It was one of the oldest monasteries on ancient Bavarian soil. Until the beginning of the 12th century it was Benedictine, but afterwards became a collegiate foundation.
It was dissolved during the secularisation of Bavaria in 1802. The premises and the abbey's seven farms passed into private ownership, while St. Zeno's church, with a house for the priest, became the parish church of Isen.
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.