Hainburg Castle, also known as Heimenburg, was built by Henry III the Holy Roman Emperor around 1050 to protect the traffic in Danube. It was enlarged in the mid-13th century. The castle was besieged in 1619-1620 by Hungarian army and conquered in 1683 by Ottomans.
After the new residence was built in 1742 the old castle was left to decay. Today Hainburg castle can freely be visited. A nice castle ruin, giving great views over the medieval town below and the surrounding countryside.
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.