The castle at Carmarthen, on its rocky eminence overlooking the River Twyi, must have dominated the medieval town just as, a little way to the east, the Roman fort must have dominated the Roman town a thousand years before.
The castle was converted into a prison in the 18th and 19th centuries, and the building of the Council offices has also not helped its appreciation as a military entity. However, enough remains to make a visit worthwhile.
The castle is first mentioned in 1094, when the name Rhyd y Gors is used but the earliest castle may have been sited elsewhere – perhaps further down the river. After 1105 the annals refer to Carmarthen by name, so by then certainly, the Norman castle was on its present site.
The castle evidently became important early on, and passed into the hands of the crown. Carmarthen quickly became the administrative centre of south-west Wales as it had been under the Romans, and inevitably underwent a series of attacks and rebuilding episodes during the turbulent struggles between Welsh and English in the 12th and 13th centuries.
A survey of the castle in 1275 refers to a dungeon, a great tower, a gatehouse, hall, kitchen and chapel, all of which apparently needed repair, and from 1288-9 much rebuilding took place; this probably included the construction of the stone curtain wall. Further buildings were added in the 14th century, including the present gatehouse and the south-west tower.
The castle became the county prison in 1789 and the building of the gaol in 1869 effectively destroyed the open space of the outer ward.
Surprisingly few traces survive of the medieval town of “New Carmarthen,” which grew up around the castle. The town walls and four gates, the Augustinian priory and the Franciscan house of the grey friars, have all disappeared. A small section of Civil War defences, thrown up by the Royalists, survives on the south-west of the town. They are known as “The Bulwarks,” and consist of an earthwork bank and a well-preserved four-sided bastion.