Nitra castle was built in the 11th century on the place of an earlier fort. The core of the castle is St. Emmeram's Cathedral with the Bishop's residence, with several different parts. The oldest surviving part is the Romanesque Church of St. Emmeram from the 11th century. The other two parts of the cathedral are the originally Gothic Upper Church from the 14th century, and the Lower Church from the 17th century. Vazil´s Tower is another remaining part of the medieval fortification. According to a legend, Vazil, king Stephen´s nephew, was imprisoned in a dungeon supposed to be in the Tower´s underground.
The originally Gothic Bishop's Palace got its present Late Baroque appearance in the 18th century. There are also surviving parts of the castle fortifications, the majority of which were created in the 16th and 17th centuries and smaller part from the Middle Ages. The church is currently being remodeled.
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.