The motte-and-bailey castle at StClears is situated on the junction between the Taf and Cynin rivers, probably at the limit of navigable water for the shallow-draught boats that the Norman settlers would have used.
Giraldus Cambrensis mentions StClears Castle by name as the home of 12 archers who had murdered a young Welshman who was 'devoutly hastening to meet the archbishop' presumably to offer himself as a crusader.
StClears does figure briefly in the Glyndwr uprising in 1405, when it was besieged and presumably captured along with the castle at Carmarthen.