The Kastel Fortress in Banja Luka is medieval but is situated on the site of previous fortifications going all the way back to Roman and even pre-Roman times. The fortress is relatively well-preserved, and is one of Banja Luka's main attractions, situated on the left bank of the Vrbas river in the very center of town.
The site has been fortified since Roman times, but the current walls and architecture were made mainly in 1490s by Ottoman reign.
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.