Cardiff Castle's fanciful little brother sits perched atop a thickly wooded crag on the northern fringes of Cardiff. It was the summer retreat of the third marquess of Bute and, like Cardiff Castle, was designed by oddball architect William Burges in gaudy Gothic-revival style. Raised on the ruins of Gilbert de Clare's 13th-century Castell Coch (Red Castle), the Butes' Disneyesque holiday home is a monument to high camp. An excellent audio guide is included in the admission price.

　　Lady Bute's huge, circular bedroom is pure fantasy – her bed, with crystal globes on the bedposts, sits in the middle beneath an extravagantly decorated and mirrored cupola, with 28 painted panels around the walls depicting monkeys (fashionable at the time, apparently; just plain weird now). The corbels are carved with images of birds nesting or feeding their young, and the washbasin is framed between two castle towers.

　　Lord Bute's bedroom is small and plain in comparison, but the octagonal drawing room is another hallucinogenic tour de force, the walls painted with scenes from Aesop's Fables, the domed ceiling a flurry of birds and stars, and the fireplace topped with figures depicting the three ages of men and women. The tower to the right of the entrance houses exhibits on the castle's history.

　　Stagecoach buses 26 and 132 stop at Tongwynlais, 30 minutes from Cardiff and a 10-minute walk from the castle. Bus 26 continues to Caerphilly Castle, and the two castles can be combined in a day trip.