Hackås Church was built in the 1100s and is probably the oldest in Norrland area. In 1770-1771 it was enlarged and the church got its present appearance. There are frescoes from the 13th century in apsis. The belfry was erected in 1752.
References:I visited church in 1993 and undersold that part of original structure had boon place of pagan worship before becoming church.
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.