St David's Church was founded in 1187, built on the site where a famous synod was held in the sixth century. According to local legend, it is said that during this synod, which St David addressed, the flat ground rose into a mound beneath his feet, allowing him to be better seen and heard by the vast crowd that had gathered to hear him speak. The church supposedly stands on that same mound. It's possible that, in reality, it was built on the site of a Bronze Age barrow.
The central tower dates from the 12th century, which, in medieval times, had five bells in its belfry. Today there is only one bell, which was given to the church by John Inglis Jones of Derry Ormond in 1874. The 12th century nave and chancel were taken down in 1832, being beyond repair, and replaced in 1833–34. The new building was of poor quality, however, and the nave as it stands today was rebuilt in 1874, and the Chancel in 1886.
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.