enilworth Castle was founded in around 1120 by Geoffrey de Clinton who was Henry I's Lord Chamberlain. The castle he built was probably a wooden motte and bailey type construction. If there was a motte on the site it would probably have been located where the current keep now stands. The stone keep that now stands at the castle was most likely built by Geoffrey's son, Geoffrey II during the reigns of King Stephen or King Henry II and is built of soft red sandstone with 14ft thick walls. The keep is rectangular, being roughly 90 feet by 60 feet and around 80 feet high. At the corners are towers that project out from the main walls. Originally the windows of the keep would have been small openings common for the time in which it was built, but in Elizabethan times the keep was altered and much larger Tudor style windows inserted.
At first the castle was leased to the king in the time of Henry II and then some time later it became the property of the crown. The castle was used by Henry II, King John and King Henry III who between them improved the defences greatly. In the time of King John the Finham brook was dammed so that a moat was formed on the southern, western and eastern sides of the castle. This created a large expance of water that made the castle almost impossible to capture. Castles with a similar sized lake used for protection include Caerphilly Castle in South Wales and Leeds Castle in Kent. On the northern side of the castle a deep ditch was dug to provide defence. It was on this northern side that a gatehouse served as the main entrance to the castle. On the southern side of the castle the top of the dam also provided access to the castle. The narrow strip of land was protected by two tower gatehouses, one at each end.
The layout of the castle consists of a large outer ward surrounded by a curtain wall. Offset to the south-west is an area of higher ground where the keep and inner bailey are located. Several towers are built into the outer curtain wall including Lunns Tower and the Water Tower on the east side, Mortimer Tower protecting the southern entrance and Swan Tower on the north-west corner.
In 1243 King Henry III granted the castle to Simon de Montfort but later Simon became Henry's enemy and was defeated and killed at the battle of Evesham. After the battle of Evesham Simon's son held out at Kenilworth Castle against King Henry III for six months until finally running out of food and water. Edmund Earl of Lancaster, King Henry III's son, was then granted ownership of the castle. The Lancasters were then associated with the castle including John of Gaunt, Earl of Lancaster, whose son became King Henry IV and during his reign the castle became a royal residence again.
