Castell Coch, meaning Red Castle in Welsh, is a perfect fairytale castle. This romantic creation of the Victorian age was designed by William Burges for the 3rd Marquis of Bute. However the castle isn't entirely fanciful, it was rebuilt from the ruins of a medieval castle and, with a few exceptions, is a fairly authentic reconstruction, at least externally.

Little is known about the history of the original castle. It started out as an earth and timber motte castle, probably built at the end of the 11th century or early in the 12th century. The castle may have belonged to the Welsh rulers of Senghennydd as both Ifor Bach and Gruffud ap Rhys are mentioned in connection with it. During the 13th century the Norman lords of Glamorgan, the de Clare family, made significant gains against the Welsh in the upland regions of their disputed territory. It was possibly at this time that the stone castle comprising a small oval courtyard with three circular towers was built at Castle Coch. The design of the building and in particular the spur buttresses at the base of the round towers suggest that it was built by the Normans. The castle appears to have been abandoned early in the 14th century.

In the late 19th century the ruined castle belonged to the 3rd Marquis of Bute, one of the richest men in the world, who owed much of his wealth to the mineral resources of his Glamorgan estates. Lord Bute had already enlisted the services of Willliam Burges to remodel Cardiff Castle in his own unique style of gothic fantasy. In 1872 he asked Burges to present a report on the possible restoration of Castle Coch. In 1875 work commenced on the complete restoration of the castle which was made into a comfortable home despite intentions to only use it occasionally in the summer. Burges died in 1881 and the castle was not completed until ten years later, however he left detailed drawings of the interiors which were completed by his team of craftsmen. The castle may have an authentic medieval look to the exterior but the interiors are pure Victorian fantasy, richly decorated and highly imaginative. After a visit to Castell Coch it is worth visiting nearby Cardiff Castle to see the ultimate example of the collaboration between Lord Bute and William Burges.