In the construction of the castle the keep was first built, it was part of the outer curtain wall which enclosed the bailey. Any buildings actually within the bailey itself would have been made of wood. See source 3. The keep was a large square building with thick walls, plinths, and defensive turrets. The keep is two storeys high, with a gallery below the wall walk. It has been changed and modified rather dramatically twice since the 12th Century and so now looks rather different to how it would have done originally. It was built up to its current height in the 13th Century, and then much later, the Earl of Leicester changed the arrow slits at first floor level to large windows. See source 4
While still belonging to Clintons, in the early 13th Century King John made extensive alterations to the original norman castle. King John added the outer curtain wall, the towers and the great lake. See source 5.
The castle soon became too prominent to be left in private hands, so the Clinton's eventually handed it back over to the monarchy. In 1244, the king appointed Simon de Montfort (Earl of Leicester) to govern the castle, and granted it to him and his wife (who was the king's sister) for life. De Montfort went on to greatly increase the fortifications of the castle and housed large amounts of weaponry there, ready for rebellion. Even though he was French, de Montfort is remembered as the initiator of democracy in England and has a place of honour in the Palace of Westminster. In his parliament of 1265 he guaranteed the ordinary people an opportunity to have a say in the governing of the country. His political opponents saw this as a contemptuous endeavour at popularity, but he found favour with the country's barons who were angry with the King's tax policy. Although de Montfort achieved great popularity, within a few months the King’s army killed him, after just before they sieged Kenilworth Castle.
The siege of Kenilworth Castle that took place in 1266 is probably one of the most historically important events to have taken place there. Simon de Montfort had become a leading rebel in opposition to King Henry III, and the Barons' War was waged for four years from 1263, in an attempt to put an end to Henry's exploitation of command. De Montfort was killed in battle at close by Evesham in August 1265. In the summer of 1266 his fellow nobles, under the leadership of Henry de Hastings, held refuge in the castle
when the King surrounded Kenilworth. The following siege of Kenilworth Castle in 1266 is the longest in English history, and confirmed the strength of the fortifications against siege machines like the Ballista brought in from London. Barges were even transported in from Chester in an attempt to enter the castle across the moat. In July 1266, the Archbishop of Canterbury stood before the castle walls and excommunicated the struggling followers of de Montfort. Unmoved by this early example of psychological warfare, the defenders dressed someone up in vicar’s clothes and excommunicated the King and Archbishop. After a six month long siege, the barons were finally overcome by disease and famine and at last were forced to negotiate a surrender, even though the castle itself still stood firm.
In 1364 gun powder was having a great effect on castle and they became less useful for defense and so John of Gaunt, Duke of Lancaster turned the castle into a palace by adding more housing, and most notably, the Great Hall. He greatly improved the castle and made it far bigger, the pride and joy of his effort being the Great Hall. The hall was very big and lavish, with high arched gothic windows and magnificent and beautiful decoration all around. It was situated on the west side of the court. South of the hall were living chambers, and there was a chapel close by. To the west, there are two wings to the hall, one at each end. The southern wing is connected to St. Lowe Tower and at the north wing, Strong Tower. See source 6. When his son, Henry Bolingbroke, became king, his possessions as Duke of Lancaster were united to the crown. Thus Kenilworth became royal property again, and stayed that way up until the reign of Elizabeth I. See source 7
In 1563, Elizabeth I granted Kenilworth castle to Robert Lord Dudley, who she liked best. A year later she gave him the titles of Baron of Denbigh and Earl of Leicester. He made many more widespread additions and alterations to the castle to continue John of Gaunt's work in turning the fortress into a palace. Some of the Norman features were modernised with fashionable Tudor to please Elizabeth, such as turning arrow slits in the keep into windows to let in more light. Queen Elizabeth I visited Robert Dudley at Kenilworth Castle in 1566, 1568, and 1575. Dudley was determined to impress her on the final trip, which lasted for 19 days and cost Dudley over £1000 every single day. He made Leicester's Tower especially for her to stay in. See source 8. It was an embelished, prestigeous and luxurios castle home. The cost of building it goes to show his dedication to Elizabeth. Masons were payed three shillings a day, this was a collosal wage considering that the avergae wage was a penny a day, if that. There were hundreds of masons working for weeks and months. He also constructed Leicester's Gatehouse as a grand entrance for Elizabeth I and had very elaborate and luxurious rooms (see source 9) , much like that which would've been in Leicester's Tower. Saying this it was still constructed with defensive features in mind. It had tall corner turrets, and could only be reached by crossing the moat. Any attackers could also be attacked from the roof. See source 10. Water displays were provided for her entertainment on the great lake that surrounded the castle, and the 'Pleasance' was set out on the North side of the castle as a pleasure garden during her visit. One particular account quotes how fireworks and guns were set off, trumpets played and torched blazed to welcome her, all of which could be heard more than twenty miles off.
After Dudley’s death, there was a dispute as to the legitimacy of ownership, and Kenilworth once more passed to the Crown. During the Civil War, Charles I withdrew his garrison and Parliament troops occupied the castle. The defensive capacity of the castle was destroyed shortly after 1656, with the Tiltyard being breached to empty the Mere, and the north wall of the Keep demolished.