The so-called Piasts' Castle in Gliwice dates back to the mid-14th century. It consists of a tower from 1322, which was originally part of the city walls, and an adjoining building which was probably an armory. Modifications were carried out in the 15th century, between 1558-61 it became the residence of Friedrich von Zettritz. Later it was an armory, a jail, a magazine and since 1945 a museum. Between 1956-59 it was thoroughly rebuilt and partially reconstructed. Since that time it is claimed to be a Piast castle, although no sourced evidence backs this claim. Since 1959 the castle has been part of the Gliwice Museum.
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.