Llantrisant Castle, once a proud edifice in medieval times, lies at the central core of the old hilltop town and represents a magnificent towered medieval fortress now reduced to fragments.

Its remains of a partial tower and small bailey make it the only medieval monument in the county borough and these are protected by Cadw's Scheduled Ancient Monument listing. The castle is a small Glamorgan courtyard castle with its commanding panoramic views of the Vale of Glamorgan and the north Devon coastline.

Tradition that Robert Fitzroy, the first Earl of Gloucester, Lord of Glamorgan (died 1147) built the castle is unproven, but a Norman church built from around 1096 onwards supports claims for an early foundation of the castle. The timber defence with ditches could have been developed as a stronghold. 

We can be certain that Llantrisant Castle was fortified in 1246 on the orders of Richard de Clare, Earl of Gloucester and Lord of Glamorgan as the administrative centre of the lordships of Meisgyn and Glynrhondda in the kingdom of Morgannwg and has stood as a landmark to the Norman French influence in South Wales for almost eight hundred years.

At the height of its power Llantrisant was rated as 'second only to Cardiff in military importance' as De Clare needed an administrative centre for annexed Welsh lands in the hill district of Meisgyn and where better than the elevated and defensible position of Llantrisant.

He had secured possession of his estates in 1243 and began to consolidate his rule in Glamorgan. The boundary of effective administration was extended northwards into the hills and valleys when Hywel ap Maredudd, the Welsh lord of Meisgyn, was defeated in 1244-5 and his lands swallowed by de Clare’s bureaucracy.

A record of 1246 clearly states that Earl Richard “fortified the castle of Llantrisant (Castrum de Lantrissen) having driven out Hywel ap Maredudd” which doesn’t exclude the possibility that this building involved a refortification of an earlier castle. The stone castle is likely to have been built on the site of an earlier timber fortification erected by Lord Gwrgan ap Ithel and repaired, if not rebuilt by Einion ab Collwyn after the invasion of Fitzhamon. 

The castle is sited on a projecting spur of pennant sandstone from the steep southerm slope of the Llantrisant hillside. When the Gigfran (Raven) Tower was intact, these views stretched across the conquered south and the perilous north or Blaenau.

Its strategic position, guarding the important route from the upland to the lowland, is very apparent. It probably had two towers, with the second to the south which adjoined a curving out court, presumably also walled and in this area the Guildhall – a medieval court house – stands.

In 1252 Margaret, De Clare’s fifth child, was born in the castle while his eldest son, Gibert “The Red” went on to build Caerphilly Castle in 1268. Certainly by 1262 the small borough of Llantrisant was developing rapidly beside the castle walls although it suffered capture and despoilment in the wars and riots of the closing years of the 13th century and earlier 14th century.

Edward II

Edward II (25 April 1284 – 21 September 1327) was King from 1307 until he was deposed in January 1327. The fourth son of Edward I he became heir to the throne following the death of his older brother Alphonso. Beginning in 1300, Edward accompanied his father on campaigns to pacify Scotland, and in 1306 he was knight at Westminster Abbey. Edward succeeded to the throne in 1307. In 1308, he married Isabella of France, the daughter of King Philip IV in an effort to resolve the tensions between the English and French crowns.

Edward had a close and controversial relationship with Pierres Gaveston, who had joined his household in 1300. Gaveston's arrogance and power provoked discontent both among the barons and the French royal family, and he was exiled. On Gaveston's return, the barons pressured the King into agreeing to wide-ranging reforms called the Ordinances of 1311. The newly empowered barons banished Gaveston, to which Edward responded by revoking the reforms. Led by the Earl of Lancaster a group of the barons seized and executed Gaveston in 1312, beginning several years of armed confrontation. English forces were pushed back in Scotland, where Edward was decisively defeated by Robert the Bruce at Bannockburn in 1314.

Hugh Despenser the Younger, became close friends and advisers to Edward, but in 1321 Lancaster and many of the barons seized the Despensers' lands and forced the King to exile them. In response, Edward led a short military campaign, capturing and executing Lancaster. Edward and the Despensers strengthened their grip on power, revoking the 1311 reforms, executing their enemies and confiscating estates. Opposition to the regime grew, and when Isabella was sent to France to negotiate a peace treaty in 1325, she turned against Edward and refused to return. Isabella allied herself with the exiled Roger Mortimer, and invaded England with a small army in 1326. Edward's regime collapsed and he fled into Wales, where he was captured in November. Edward was forced to relinquish his crown in January 1327 in favour of his fourteen-year-old son and he died in Berkeley Castle on 21 September, probably murdered on the orders of the new regime.