Carmarthen Castle is a large and important castle but it has a disputed foundation, originating in 1109 or the late 13th century. Remains of the high medieval castle, including a shell keep, gatehouse and two towers, are obscured by modern buildings, notably County Hall. The site was used as the county gaol from the eighteenth century (nprn 100074).

It is associated with the Medieval and later borough (nprn 33058).

Repairs and additions to castle were made throughout the thirteenth to fifteenth centuries, and there are notes of expenditure on painted hangings from 1435-7. The gaol, designed by John Nash, was located on the east side within the curtain wall. Extant remains include the motte, donjon with towers, gatehouse, and southwest drum tower.

The castle was the site of a siege in 1233-4:
In 1233, Richard Marshall, Earl of Pembroke, laid siege to the castle of Carmarthen, which successfully resisted his assaults for three months, when the arrival of succours by sea compelled the earl to abandon his enterprise.

1233: Maelgwn Fychan ap Maelgwn ap Rhys and Owain ap Gruffudd and Rhys Gryg and their sons and the host of Llywelyn ap lorwerth and the host of the earl of Pembroke gathered together against Carmarthen. And they laid siege to it for three months, and they made a bridge upon the Tywi. And then the sailors came armed, with the tide, to break down the bridge. And when the Welsh saw that their expedition would be fruitless, they returned to their lands.

"towards the end of this year [1233] . . . earl Richard [Richard MarshalI, earl of Pembroke], Rhys Gryg, Maelgwn Fyhan, and Owain ap Gruffydd beseiged the fortress [of Carmarthen] for three months and by building a temporary bridge across the river Towy, shut off all hope of relief from . . . the Bristol Channel. . . in March 1234, Henry de Turberville sailed with a fleet from Bristol and . . . broke up the improvised bridge, with great slaughter of its defenders."

Sources include:
See Ludlow 2003 (Carm. Ant. 39), 147-151.
Cadw listed buildings database
Samuel Lewis, A Topographical Dictionary of Wales, 1833.
Thomas Jones, The Chronicle of the Princes, 1955, p.233.
J.E.Lloyd, A History of Carmathenshire, vol I, 1935, p.180.
Richard Suggett, Painted Temples: Wallpaintings and Rood-screens in Welsh Churches, 1200–1800, (RCAHMW 2021), pp. 110.

RCAHMW 2021