Rüeggisberg Priory was founded between 1072 and 1076 by Lütold of Rümligen. He granted the property and estates to Cluny Abbey making it the first Cluniac house in the German-speaking world. Under Cuno of Siegburg and Ulrich of Zell the first cells were built. Construction of the Romanesque church lasted from about 1100 to about 1185, of which there still remain the north transept and parts of the crossing tower. The Priory was dependent on Cluny Abbey and normally had a prior and two to four monks from Cluny. In 1148, it had two priories that were dependent on Rüeggisberg, in Röthenbach im Emmental and Alterswil.
At its peak the priory controlled estates throughout what is now the Canton of Bern, including Guggisberg, Alterswil, Plaffeien and Schwarzenburg as well as scattered farm houses and vineyards on the shores of Lake Biel.
The priory was one of the most important monastic houses of Switzerland during the Middle Ages, but in the late medieval period decline set in, and in 1484 it was incorporated into the newly built college of the Augustinian Canons of Bern Minster. By 1532, when much of the town was destroyed in a fire, the Priory was abandoned. The church was shut down in 1541 during the Reformation. The monastic buildings thereafter served as a source of building stone and partly as a barn.
Between 1938 and 1947 on an archaeological dig the old foundations were again laid bare, as may be seen in the little museum next to the rectory.
The ruins are generally open to the public, though they may be reserved for picnics or other gatherings. Each November an advent market is held in the ruins and over the years a variety of open air plays and concerts have been held here. Between Easter and September, church services are held monthly in the ruins.
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.