Llansteffan Castle sits on a much older Iron Age promontory fort, proving Llansteffan has been inhabited for several millennia. The hill where the castle stands commands the River Tywi estuary. The hill would have been stripped of trees so that foot soldiers were vulnerable to attack by archers. The original earthworks can still be seen and were used as part of the modern castle's defence system - the castle proper rests within the earthwork rings.
The castle was built by the Normans after 1100 as part of their invasion of Wales and granted to the Marmion family before passing to the de Camvilles through marriage.
It was captured by Maredudd ap Gruffydd in 1146 against the forces of Maurice FitzGerald, Lord of Lanstephan and his brother William FitzGerald, Lord of Emlyn who were the leading Norman settlers of the region. The castle was retaken by the Normans in 1158. Llywelyn the Great recaptured the castle for the Welsh in 1215 and taken back by the de Camville family sometime after 1223. The castle fell to Llywelyn ap Gruffudd in 1257 but returned to the de Camvilles by the 1260s.
The castle was captured twice by the forces of Owain Glyndŵr in 1403 and c.1405. It was recaptured by Sir John Pennes in 1408. The castle was later granted to the Crown and the two-tower Gatehouse was converted into a residence.
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.