St. Nicholas parish church dates from the 12th century. Its western wall, with a Romanesque structure, has preserved the original shape. Also, Romanesque are the church round tower and the matroneum. In the Middle Ages, Żarnów's church was located by a busy merchant road from Sandomierz to Greater Poland. The town itself was at that time located to the south and west of the church. In 1510, a Gothic presbytery was added.
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.