Carmarthen Castle is an early 12th century earthwork motte and bailey fortress, founded by King Henry I. Overlooking the River Tywi, the fortification was besieged, burnt and captured by various Welsh Princes, in 1137, 1146, 1215 and 1405. Partly rebuild in stone from 1181, William Marshall the Younger, earl of Pembroke strengthened the defences in 1223. Sadly only the western side of the castle remains, with the large motte supporting a truncated 13th century shell keep. The high curtain wall is flanked by the South-west Tower on the angle, the Square Tower and an early 15th century twin-towered gatehouse. Slighted after the Civil War, the County Hall now stands within the bailey, having replaced the county gaol of 1789. 3 miles south is Castell Moel and 9 miles south is Kidwelly Castle.