Ruotsinsalmi fortress was built by Russians in 1790-1796. It was part of the South-Eastern Finland fortification system which was planned to defence St. Petersburg. The sea fortress was located to islands in front of the city of Kotka and Kyminlinna fortress. It contained three main strongholds (Fort Katarina, Fort Elisabeth and Fort Slava) and several redoubts and artillery batteries.
Ruotsinsalmi fortress lost its original defensive value only couple of years later, when rest areas of Finland were joined to Russia after the Finnish War (1808-1809). It was disbanded in the 1830's and during the Crimean war (1855) Anglo-French fleet destroyed the empty fortress permanently.
Today individual remnants of fortresses can still be found for instance beside Catherine’s path and on the island of Tiutinen. Also Fort Elisabeth's embankments have been renovated in recent years. The island is easily accessible by regular boat services in the summer.
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.