Sundbyholm was originally owned by the Order of St. John, who had an abbey in Eskilstuna. After the Reformation it was confiscated to the Crown. The Sundbyholm Castle was built by the Admiral of the Navy Carl Gyllenhielm, son of King Charles IX of Sweden. The estate was given to him in 1627. The castle was later enlarged by Seved Bååts.
Sundbyholm Castle is known for the beauty of its grounds and nearby environs. It has been the subject of several paintings and drawings, the most famous of which is "The Old Castle" by Prince Eugen, Duke of Närke.
Today Sundbyholm is a hotel and offers facilities for conferences, parties and weddings.
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.