Fårösund is a decommissioned fortress, built from 1885 to 1886. Sweden's capacity to protect its neutrality was questioned after the Crimean War 1854–56. England and France persuaded Sweden to fortify the inlet at Fårö with artillery batteries and naval mines. The fortress consisted of three fixed batteries. At the turn of the century, the batteries were reconstructed. The batteries I and II were given modern quick-firing 57 mm guns, four per battery. In 1919 the fortress was closed down and all equipment removed. After the fortress was closed down and was taken over by the Swedish Prison and Probation Service in 1919, a penitential center was establishment. The fortress had been proposed as a detention center for social dangerous offenders, if and when legislation for such came about.
Today the fortress is a hotel and restaurant.
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.