The walls of the ancient Fishermen's Chapel are reputed to date from the middle of the 6th century, but some authorities give a later date. It is however only a few monastic chapels survived the destruction of over fifty others at the hands of the Reformers in the 16th century. The material used in the chapel is the same as was used in the parish church: limpet shells crushed and dissolved with boiling sea-water. The stone roof was raised in the 14th century. The monks of that period evidently found the roof too low and squat for wall paintings. These were discovered in 1918. After a severe storm, colour was revealed on the ceiling and a picture of the 'Assumption' was seen, but in a damaged condition. But underneath the plaster was found another painting, 'The Annunciation', of about 1310-1315 A.D. At the foot of this painting are seen fourteen figures, supposedly members of an old Jersey family, the head of which had paid for this painting.The floor was restored to its earlier level in the 1980s to the medieval level, and the 'low, squat' aspect of the chapel which appears in early photographs is now gone, as the proper proportions can be seen.
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.