There are several fortresses and bastions surrounding Göteborg and one of the more interesting ones is the impressive Bohus Fortress... Historically the area has been subject to many confrontations between the Swedes, Norwegians and Danes.
King Haakon V Magnusson of Norway started the construction of Bohus Fortress in 1308, which at the time was part of Norwegian territory, and it served as the main Norwegian defense against Sweden along the coast. At one point during the Northern Seven Year’s War (1563-1570), the fortress was seriously damaged when 250 Swedish soldiers successfully stormed the northeastern-most tower. The Norwegian commander sent a volunteer to blow up the ammunition stores underneath the tower, killing the Swedes and repelling the attack.
In 1658 Bohus fortress was given to Sweden permanently under the terms of the Treaty of Roskilde, but since it no longer lay on the border it was of minimal future use to Sweden for defense purposes and was subsequently turned into a prison instead. At the end of the 18th century it was decided that the now unused fortress should be demolished. After two months of work the money allocated for the task was spent entirely and much of the fortress was left intact.
Today the fortress serves as a museum and is open for tours during the summer. There are also other activities being held there such as Medieval Days, theater and concerts.