Mallersdorf was formerly a monastery of the Benedictine Order and is now a Franciscan convent in Mallersdorf-Pfaffenberg.
The monastery, dedicated to Saint John the Evangelist, was founded in 1107 by Heinrich of Kirchberg, a ministerialis of Niedermünster in Regensburg, and settled by monks from either the monastery of Michelsberg in Bamberg or St. Emmeram's Abbey in Regensburg.
Under Abbot Eppo (1122-1143) the reforming influences of the monasteries of St. Georgen im Schwarzwald and of Hirsau had a significant impact. At this time the community was subordinated to Otto I, Bishop of Bamberg and placed under the direct protection of Pope Innocent II (1130-1143). In 1136 Abbot Eppo dissolved the double monastery (i.e., including both men and women) which seems to have been there until that time; the women's convent was transferred to nearby Eitting. In the 12th century there was church building in the romanesque style, in the 13th a period of spiritual awakening, and in the 14th the reforms led by Kastl Abbey. In the mid 16th century the abbey narrowly escaped dissolution. The monastic grammar school enjoyed an excellent reputation.
The abbey was finally dissolved in 1803 during the secularisation of Bavaria. The assets and estates were auctioned off. The monastery buildings were used from 1807 as offices for local officials.
Since 1869 Franciscan sisters have lived at the site.
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.