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:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.