Skansen Kronan is a redoubt built in the later half of the 17th century according to the plans of Erik Dahlberg. Skansen Kronan was introduced in 1698 and was fitted with 23 guns. The roof was not completed until 1700. Skansen has 4-5 metre thick walls made of granite, gneiss and diabase. Skansen Kronan was never attacked and the cannons on the inside have never been used.
The fortress and the twin counterpart, Skansen Lejonet, were built as part of the defenses against possible Danish attack on Gothenburg from the south, and thus had a similar purpose as the Älvsborg Fortress.
The fortress - originally built outside the city walls - is today situated in the city centre of Gothenburg on a hill in the city district of Haga. It was used as a military museum until 2004. Today Skansen Kronan is a private facility for conferences and private parties.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.