The 'Ravelijn op den Zoom' (ravelin) is the last remnant of the fortifications designed by Menno van Coehoorn. The ravelin consists of a island with earthen and stone walls, surrounded by a wide moat. The ravelin is one of the few remaining parts of the extensive fortification system around the city. The fortress was so ingeniously designed that it was assumed that it could not be taken and therefore got the nickname 'La Pucelle' (Virgin). In 1747 the city nevertheless became occupied by French troops.
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.