Substantial remains of a Norman castle built high on cliffs overlooking the Twyi estuary south of Carmarthen in South Wales. The Normans built their castle on the site that had been used since the Iron Age due to its easily defendable location. Consisting of a strong gatehouse, outer and inner baileys, much of the outer walls on the castle remain and date from the middle to late thirteenth century.
The Norman Llansteffan Castle was attacked by Owen Glendower. Glendower may have held the castle for a short time until it was retaken by Sir John Penress (Pennes).