Cardiff Castle was founded by the Normans in 1091, on the site of a Roman fort whose remains can still be seen. The castle's most famous occupant was Robert, Duke of Normandy, who was imprisoned there by his younger brother, King Henry I of England, from 1106 until 1134. In 1158 it was the scene for a daring kidnapping carried out by one Ifor Bach (Ivor the Little). The Welsh took it again in 1404, under Owen Glendower. In 1488, it came into the possession of Jasper Tudor.

During the 19th century, a new mock-medieval castle was built to the design of William Burges, architect to the Earl of Bute, as a fairytale residence. The castle was later given to the city of Cardiff by the Bute family. It is now a popular tourist attraction, and houses a regimental museum in addition to the ruins of the old castle and the Victorian reconstruction.