The first castle in Neath was located west of the river near the Roman fort of Nidum, and was a timber fortification in a motte and bailey structure. When Richard de Grenville founded Neath Abbey close by, he abandoned this original castle, and it may have been used by the monks as a source of building material.
A second castle on the opposite bank of the river, in what is now the centre of the town, is first documented in 1183; shortly afterwards, William de Cogan, son of Miles de Cogan, was appointed constable. This second castle was built by Gilbert de Clare, 5th Earl of Gloucester. During the 13th century, being a Norman stronghold, it was subject to attack by the Welsh, notably by Llywelyn the Great, who captured it in 1231 with help from a local Welsh lord, Morgan Gam. Following this, it was substantially rebuilt by Richard de Clare, 6th Earl of Gloucester, Gilbert's son.
It was taken again, and this time destroyed, by Humphrey de Bohun, 4th Earl of Hereford, in 1321, during the rebellion against King Edward II of England. Its owner, Hugh Despenser the Younger (who had gained the lordship through his marriage to the heiress Eleanor de Clare), rebuilt it, possibly with the addition of a gatehouse. In 1376, one Roger Kyngot was the constable, and the castle was rebuilt in stone in 1377; that is probably when the great gatehouse was built, which is the main surviving feature. The castle was in use until the 17th century, and has been a recreational area for the town since the 18th century.
References:The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.