Gradually, from the late eleventh and through the twelfth century, some earth and timber castles were rebuilt in stone, with
- a stone keep instead of the wooden tower on the motte.
- a stone curtain wall instead of the wooden palisade.
- a stone tower instead of the bailey gate.
However, some castles were built in stone from the beginning. Chepstow Castle (Monmouthshire) was the earliest stone castle in Wales. Chepstow originally consisted of a long rectangular tower, two storeys high, which included the owner’s hall and private rooms, and perhaps quarters for soldiers and storerooms in the basement. Entry was at first-floor level by an external wooden stair, which may have been removable in times of danger.
Many other stone keeps were built throughout the south and east of Wales in the early twelfth century: Ogmore Castle, near Bridgend, is a fine example.
Sometimes the timber palisade around a motte was rebuilt in stone, and this is called a shell keep. Two examples of shell keeps in Wales are Cardiff Castle (owned by Cardiff City Council and open to the public) and Tretower Castle, Powys (Cadw). From about 1200 onwards, round keeps were built, because it was easy for attacking armies to damage rectangular keeps by undermining them at the corners (knocking out the corner stones and setting a fire underneath to make a hole for the soldiers to enter). Round keeps built between 1200 and 1240 can be seen at Pembroke Castle, Pembrokeshire (private castle open to the public), Bronllys Castle, Powys, and Skenfrith Castle, Gwent.
A stone keep was not only a stronghold but also a residence, with accommodation for the lord and his household. In the keep the furnishings would probably have been sparse. The hall, for example, may have contained a table, benches and chairs for the lord’s family. Stone seats were often built into the walls or windows. The floor would have been covered with rushes. The inside walls were usually plastered and painted, and it is still sometimes possible to see traces of paint that once decorated the walls.