Before the Norman invasion of the 12th century, Swansea was little more than a temporary home for Scandinavian traders who were attracted to the site by its natural harbour at the mouth of the River Tawe. However, with the invasion of the Normans in 1106, Swansea was to burgeon into the headquarters of Gower, the largest commote in Wales.
Following the murder of Hywel ap Goronwy, the Welsh ruler of Gower (Gwyr), the Norman King of England, Henry I, appointed his close friend, the first Earl of Warwick, Henry de Beaumont (also known as Henry de Newburgh) as Lord of Gower. As a priority, de Beaumont needed to find headquarters for his command and discovered the ideal location on the west bank of the River Tawe. From this vantage point he would be able to maintain order of the peninsula and the stretches to the north, towards the river banks of the Aman and Twrch, which marked the old boundaries of Gower. No doubt he was also concerned to protect the natural harbour from attacks via the sea, knowing the area to be popular with Norse raiders in the past.
In true Norman tradition he built a motte and bailey style castle. A natural mound along the western bank of the river was incorporated into the motte whereupon a timber keep was constructed. This in turn was defended with the ditch and earth bank of a small inner bailey. A large outer bailey defended the western side of the castle, with the river completing the defense on the eastern side.
The castle was joined by St. Mary's Church to the southwest and was eventually surrounded within the town walls during the early 14th century. These two buildings dictated the placing and development of the early streets and markets of Swansea.
In order to maintain a good level of security from within the town, newcomers were encouraged to settle and trade, by the granting of a charter. The charter was an agreement made by the lord giving all citizens of the borough freedom from feudal obligations with extra rights and incentives, in exchange for a fixed yearly rent for plots of land and strict military allegiance. Swansea's first charter, written between 1158 and 1184, was one of the earliest granted to any town in Wales, and was agreed by William de Newburgh, the grandson of Gower's first lord, Henry de Beaumont.
Nevertheless, despite the town's healthy population and prosperous trading, the castle and market town suffered many attacks from the Welsh. After being ravaged during raids from Llywelyn the Great in 1215 and Rhys Gryg in 1217, the castle was rebuilt in stone on the same site in the 1220's, by John de Braose, the Gower Lord of the time, and it is estimated that the town walls were constructed by William de Braose III between 1306-1332.
Extensions were made to the south east corner of the castle some time before 1347, and this became known as the 'New Castle'. The architecture of the New Castle has been largely attributed to Henry de Gower, Bishop of St. David's (1328-47), as the distinctive arcaded parapets are also to be seen in de Gower's palaces at Lamphey and St. David's. Recent historians have theorised that the absentee Gower Lord, de Mowbray, may have employed the Bishop's masons after seeing their work at St. David's Hospital. This would accurately date the work of Swansea's New Castle to the year 1332.
The castle was finally seized by the Welsh under the rebellion of Owain Glyndwr between 1400-10. This wreaked devastation for the Lordship of Gower. By the late 16th century the castle had become ruinous and was described in a survey as an 'ancient decayed building called the New Castle'. The following centuries saw various uses of the surviving chambers of the ruined castle, one such example being its use as a debtor's jail until around 1858.
It is now difficult to imagine the original large scale of Swansea Castle. Only fragments of the New Castle remains to be seen today. The castle's north and south blocks, connected by a short stretch of curtain wall, are all that survives its turbulent history. The impressive parapets of the south block clearly show the hallmarks of de Gower's rich architecture whilst the 18th and 19th century adaptation of the north tower has not completely removed some of the castle's original features - such as the cross arrow slits. The castle ruins now lay adjacent to the British Telecom tower block, its rugged and fragmentary appearance standing in stark contrast to the modernity of its mirror-windowed tower face.