The castles described on this page are not medieval. They were built between one and three thousand years before the medieval period but it's important to understand why and where they were built as many still exist today and were reused in medieval times.
To avoid being attacked either by fellow humans or wild animals and without the luxury of a stone castle the best defence for Iron Age people was to live somewhere that was difficult for those attackers to get at. This is how primitive people planned their defences. By living somewhere from which they could see attackers coming and somewhere they could easily defend early humans were able to survive. A common tactic was to live on top of a hill which could be made steeper using banks of earth and surrounded by water filled ditches. These fortifications are now known as hill-forts.
Cadbury Castle has been occupied on and off since around 5,000 years ago. It consists of four sections of earth works that rise some 500 feet. Archaeological digs at Cadbury have found remains from the Iron Age including pottery, arrow heads and axes. Evidence suggests that Wooden defences were used to protect the top of the castle. Although the wood has now rotted away there are the remains of holes that show where the posts would have been located. During the Roman occupation of Britain the Romans attacked the castle killing its inhabitants or forcing them to flee. The Romans had no use for the castle so they burnt it down and destroyed the ramparts.
The castle appears to have been abandoned until the time of the mythical King Arthur when wood and stone ramparts were constructed.
How good a hill-fort was at defence was based on the height of the banks and depth of the ditches. The remains of many hill-forts survive to the present day including Cadbury Castle and Old Sarum. Where possible the people who planned these fortifications used natural defences such as high cliffs and and rocky coastlines. Having several sides of the fortification protected by unclimbable cliffs meant there was less area for a defender to defend. The only problem with this type of design was that it was difficult to escape if attackers did manage to penetrate the fort.
When the Romans arrived they brought their own methods of defence. Their forts tended to consist of large rectangular compounds built from either wood or stone. Wooden forts were built where stone was not available or where there was less need for a strong defence. A ditch around the outside of the fort added an extra level of security. The purpose of the Roman fort was to house a garrison of soldiers. An existing example is Portchester Castle shown on the left. Portchester is rectangular in shape and the walls have semi-circular jutting out walls called bastions. It is built on the shoreline so that it could be resupplied by sea and its location in the natural harbour of Portsmouth was so important to the Normans that they built their own castle within the walls of the Roman structure. The Norman additions to the castle are shown in black
Several Iron Age hill forts were used in medieval times. The most notable of which must be Old Sarum. Old Sarum is located near Salisbury in Wiltshire. This large hill fort was big enough to have a castle, a village and cathedral within its boundaries. The barons pf England did homage to William the Conqueror at Old Sarum after the Norman Conquest. The hill fort was abandoned in around 1220 when it ws decided to move the settlement nearer the river Avon several miles to the South. The new cathedral at Salisbury was the result.
After the Romans left some of the old abandoned ancient forts were refortified by the Britons to protect themselves from the invading Saxons. A good example of this is Cadbury Castle (or Hill Fort) in Somerset. The site is so big it could hold several entire armies at one time and is supposed to be a site that King Arthur used. The Saxons then reused these ancient strongholds, adding their own defences and many were in use in the medieval era. The diagram above shows the layout of the fort. It consists of a series of steep banks and ditches designed to keep attackers out. The entrance to the fort is via a series of twists and turns designed to confuse the enemy.
The Normans resued Portchester Castle, strengthening the walls and buildings a Norman Keep in one corner of the rectangular fort.