Mosynopolis , of which only ruins now remain in Greek Thrace, was a city in the Roman province of Rhodope, which was known until the 9th century as Maximianopolis. The city of Maximianopolis appears in written sources from the 4th century on. Its fortifications were renewed by Byzantine emperor Justinian I, and it was later a base for operations by Emperor Basil II in his wars against the Bulgarians.
In the 11th century, the city was the center of a district (bandon) in the theme of Boleron, and Anna Komnene reports in her Alexiad that there were many Manichaeans living in Mosynopolis in the late 11th/early 12th centuries. The town was captured in 1185 by the Normans, while the monk Ephrem says that the city was captured in 1190 by Frederick I, Holy Roman Emperor. The Battle of Messinopolis, in which the Bulgarians defeated Boniface I, Marquess of Montferrat, took place nearby in 1207, and was speedily followed by the destruction of Mosynopolis by Tsar Kaloyan of Bulgaria.
Bishops of Maximianopolis in Rhodope were present at the 5th and 6th-century ecumenical councils of Ephesus (431), Chalcedon (451), and Constantinople II (553) and in another council of 459. From the 7th to the 9th centuries, the see is referred to as archiepiscopal, giving it autocephalous status.
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.