 This was probably the castle of "arberth" which was attacked and destroyed by Gruffydd ap Rhys in 1116, according to a chronicle in the Cotton library; the stone castle at Narberth was not built until over 100 years later.Legends as recorded in the 13th century Third Branch of the Mabinogi (concerning Manawydan fab Llŷr) mention the area of Arberth and a place called Gorsedd Arberth, thought by some authorities to be Sentence Castle.The embanked earthworks are about 15M across and the site is a Scheduled monument.