The rebuilding of Montgomery Castle in stone was commenced in the late summer of 1223 on the 16th birthday of Henry III of England, a mile to the south-east of the original site. The architect of the new castle was Hubert de Burgh who also rebuilt Skenfrith Castle, Grosmont Castle and White Castle in the Welsh Marches. From 1223 until 1228 masons worked solidly building the entire inner ward, or donjon as it was then known on a great rock above the later town of Montgomery. This work consisted of the gatehouse, two D-shaped towers and the apartments which crowded around the curtain wall of the inner ward. After an unsuccessful attack by Prince Llywelyn ab Iorwerth in 1228 the middle and outer wards were added to the castle. The castle was again attacked in 1233 which resulted in damage to the Well Tower which had to be subsequently repaired and re-roofed.