In 1069, rebels slaughtered the new Norman garrison at York. In reprisal, William I 'the Conqueror' laid waste to all the countryside form York to the Wear. Once the local opposition had been crushed through this 'Harrying of the North', William I divided out the land between his Norman lords. Alan the Red was one of these men and he was given the Borough of Richmond as a reward for his good service to William I. He started to build Richmond Castle, in stone, around 1071, choosing a natural defensive position 100 ft above the River Swale.

It's purpose was to protect Swaledale against border raids and most of the surviving curtain wall is his work.

The 100 ft high keep was started by Conan the Little, Earl of Richmond in the third quarter of the 12th century and was finished by Henry II (1154 -1189 ). The fact that the keep was built on rock, rather than on a man-made earth motte, enabled the builders to construct a very solid structure which has stood up well to the passage of time. Raised on the site of the original gatehouse it is plain and simple in design. It's purpose was military, rather than residential, as the comfortable living quarters were already sited in the south-east corner of the castle's bailey.

As one enters the castle through the barbican, on the left can be seen the east curtain wall with its towers. One deserves special mention. Robin Hood, or Lion Tower, is so called as it once held captive William the Lion, King of Scotland (1142 - 1214 ) after his defeat at Alnwick in 1174 during his invasion of Northumbria. He was released as soon as he recognized Henry II as his overlord.