The town of Bulle initially developed around its church which was, in 9th century, an ecclesiastical center of importance. The construction of the castle began certainly under the episcopate from Boniface (1231-1239). After the annexation of Bulle by the town of Freiburg, the castle became, since 1537, residence of the bailiffs'. Since 1848, it is the seat of the Prefecture of the Gruyère and receives the Court, the state police and the prisons.
Forming a quadrilateral of 41 x 44 meters, it includes main buildings on three sides. Its construction was carried out according to plans' of the Savoyard Castles, with small towers in the 4 corners.
The keep, enormous and separated by a small court, 33 meters is high and broad of 2.16m at its base. Its entry of origin is located at 9.7m ground. Less imposing, the turns of the three other angles are little towers placed in overhang in top of the walls.
This historical fortress has escaped with the fire which destroyed the city in 1805.
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.