The monastery at Kildonan was founded by a missionary St. Donnan, possibly from either Dal Riata or an Irish Kingdom. He and his monks were massacred in 617 by the local Pictish queen. In medieval times the island was held by Clan Donald. The church which currently houses the alleged sheela sculpture is thought to be a 16th century construction but there is evidence of earlier religious settlement in four cross slabs which date from the early medieval period. Records also list a religous settlement here in 725 so it would seem that the monastery continued after St Donan’s death.
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.