The Oostkerk was designed by Bartholomeus Drijfhout and Pieter Post and was built between 1648 and 1667. After Drijfhout died in 1651, the building was continued under the Leiden architect Arent van 's Gravezande, who had just completed the Marekerk in Leiden. The white organ was built by Gebr. de Rijckere from Kortrijk in 1782. Two stained glass windows from 1664 still exist in the church, and the klokkenstoel contains a bell by C. Noorden and one by J.A. de Grave, 1715.
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.