There was a church on the site of St Mary's since circa 1328, erected by Henry de Gower, Bishop of Saint David's. One Sunday morning, in 1739, the roof of the nave collapsed into the church while the congregation was waiting to enter the building. The whole structure was re-built apart from the tower. 1822 saw the church being lit by gas for the first time with thirty six lamps. The church underwent complete renovation between 1879 and 1882 by Vicar Dr Morgan. In 1896, the church was flattened and rebuilt again under the designs of Arthur Blomfield by Dean Allan Smith, though some parts of the old church survived the re-development. In February 1941 the church was extensively damaged by Bombing during the Blitz. It was not rebuilt until the 1950s.
From the 1890s the Swansea Devil stood on a set of buildings facing the west side of the church, constructed by a disgruntled rival of Blomfield's, angry at the commissioning of Blomfield's designs over his own.
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.