The castle was erected in the mid-13th century by Richard de Clare, Earl of Gloucester, the ruler of Glamorgan, to guard the newly conquered lands and an important route from the mountainous regions to the lowland zone. In 1262, the castle passed into the hands of a mighty lord, Gilbert de Clare, who made its expansion, but in 1315 the castle was seriously damaged during the Welsh attack of Llywelyn Bren. In 1326, the unfortunate king Edward II was briefly imprisoned here, before being transported to the Berkeley Castle, where he was murdered. Although the castle was still inhabited in the 16th century, it gradually fell into disrepair. In the 19th century, the Marquis Bute used the Llantrisant stone for his extensive construction projects at the castles of Cardiff, Caerphilly and Castell Coch.
Built on a small hill, the castle consisted of two cylindrical towers, strengthening the oval perimeter of the defensive walls, measuring about 30 by 25 meters, from the north and south. Relics of the portal indicate that you could get to the porch of the defenders, crowning the walls, from the north tower. Its diameter was as much as 14.2 meters, while the southern one was about 10-11 meters. From the north there was an outer bailey.
To this day, only a part of the northern tower has survived, reaching 13 meters in height. Only relics of foundations remained from the southern tower.
Website coflein.gov.uk, Llantrisant Castle.
Website wikipedia.org, Llantrisant Castle.