This building is chiefly known as a romantic folly supposedly reproducing a small medieval Welsh chieftain's stronghold, built in the 1870s, for the 3rd Marquess of Bute to a design by William Burges, and possessing the most remarkable interior decoration. However, it was built upon the remains of a genuine 13th century castle built in two stages. Evidence was found of the building having been deliberately slighted by mining.
The castle was probably founded by a Welsh lord in c1240-65 and had a round tower keep at the SW corner of a tiny D-shaped courtyard with a hall on the south side, all built of rough rubble sandstone from which the building took the name Castell Coch, or "Red Castle." It stands upon a platform commanding the gorge of the Taff and was protected towards the higher ground by a deep dry moat from the bottom of which the walls rise with a very broadly battered base. The keep contained vaulted rooms, and probably had a fourth storey and a conical roof like it has now. The walls are over 3.3m thick above the square battered base from which it rises with pyramidal spurs.
From the narrative you seem to really know your castles. Thank you for the narrative. Without it I'd been fooled to believe that it was quite an example of a military castle. Nevertheless, it is an awesome sight. Beautifully captured. Thank you.