Around 516, Saint Einion, king of Llyn, invited the Breton Saint Cadfan to move to the Bardsey Island from his first residence in Tywyn. Under Cadfan's guidance, St Mary's Abbey was built. In 1188, the abbey was still a local institution but, by 1212, it belonged to the Canons Regular. Many people still walk the journey to Aberdaron and Uwchmynydd each year in the footsteps of the saints, although today only ruins of the old abbey's 13th century bell tower remain. A Celtic cross amidst the ruins commemorates the 20,000 saints reputed to be buried on the island.
The Dissolution of the Lesser Monasteries Act of 1536, on the orders of Henry VIII, resulted in St Mary's Abbey being dissolved and its buildings demolished in 1537.
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.