Tolquhon Castle was built by William Forbes, 7th Laird of Tolquhon, between 1584 and 1589 as an extension to the earlier tower house known as Preston's Tower. Although ruined, the castle has been described as the most characteristic château of the Scots Renaissance. It is in the care of Historic Scotland and is open to the public.
After William Forbes' death his descendants continued to occupy Tolquhon until 1718, when they were forced to move out due to debts incurred by the failure of the Darien scheme. The castle subsequently decayed and is now a ruin.
The main entrance is on the north range of the castle, with the Preston Tower forming the north-east corner. The gallery occupies the first floor of the west range, while the main hall is in the south range, accessed via a stair from the courtyard. A prison was located within the south-east tower. To the north of the main quadrangle is the walled outer courtyard, with the remains of a doocot.
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.