Estonian Maritime Museum (founded 1935) is located in the cannon tower, Paks Margareeta (Fat Margaret), forming a part of medieval defence system. The exposition on the history of Estonian maritime - ship- and boat building, ports, navigational aids on the ships, lighthouses – is displayed on the four floors of the museum.
In addition to the main exposition the exchangeable exhibitions take place on the ground floor.
In the inner court historical anchors are exposed and from the roof of the tower there is a fine view over the port and Old Town.
Reference: Estonian Maritime Museum
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.