Carmarthen Castle

An earlier fort stood 1.4 kilometres to the south at Rhyd-y-gors, raised by William FitzBaldwin of Devon on behalf of William II, probably after the death of the Welsh king Rhys ap Tewdwr in 1093; it was last mentioned in 1106. The castle on the present site is dated variously to 1104, about 1106 or 1109, and is ascribed to Walter of Gloucester, though Ludlow suggests it more likely already stood when Walter was recorded in 1109 as being sent to defend Carmarthen.

The castle stands on a high terrace twenty metres above sea level, overlooking the tidal Towy above what was the lowest bridging point of the river, eleven miles from the sea. It has dominated the layout and orientation of the county town, whose streets and property boundaries run out from the site. The first works were a timber motte and bailey.

The Normans arranged for Carmarthen to be defended by local chieftains serving in a fortnightly rotation. Even so, around 1116 Gruffydd ap Rhys, a Welsh prince whose lands the Normans had taken, took the castle in a night attack, dismantled it and plundered the town.

Rebuilt, it changed hands repeatedly over the following decades. Owain Gwynedd, prince of North Wales, destroyed it in 1137 and it was destroyed again in 1143; briefly recaptured in 1144, it was taken in 1146 by Gruffydd's son Cadell, who held it for several years, and Cadell's brother Rhys captured and destroyed it once more in 1195. The castle is believed to have been rebuilt in stone in the later years of the 1100s.

Owain Glyndŵr captured the castle in 1405. Half a century later, in the Wars of the Roses, Edmund Tudor took possession of it for the House of Lancaster, and in August 1456 Yorkist troops under William Herbert took the castle and imprisoned him. Edmund died there on 1 November. His wife, Lady Margaret Beaufort, then thirteen, gave birth the following January to the boy who became the first Tudor king of England, Henry VII.

Parliamentary forces captured the castle during the Civil War, and in the mid-1600s it was slighted — dismantled — by order of Oliver Cromwell. An eight-cell jail stood in the inner bailey, and in 1789 it was converted into a new County Gaol designed by the architect John Nash; extended in 1869, it lasted until its demolition in 1936. Around 1860 a two-storey police station and lock-up went up between the outer and inner walls, holding prisoners in transit to the nearby courthouse until 1947. That building survives as Castle House.

With no further use for a prison, Carmarthenshire Council bought the Old Gaol in 1925, meaning to put a new County Hall and a museum on the site; the council's château-style County Hall was finished in 1938. The remains were listed Grade I on 18 August 1954 as "substantial remains of a major medieval castle", and the site is also a scheduled monument.

Archaeological investigation around the turn of the twenty-first century made the Square Tower and Southwest Tower accessible, and surrounding buildings were cleared to bring the castle back into view. The upper levels of the gatehouse and shell keep were opened to the public for the first time in 2003, with a grass terrace and benches made at the top of the keep's mound. Castle House now holds a museum and the town's Tourist Information Centre, and the surviving gatehouse on Nott Square, thirteen metres high, is one of the two entrances.