The average height of a curtain wall was about 30 feet. There are a few exceptions, such as at Framlingham Castle. The stone curtain wall there was 44 feet high, while Knareborough Castle's was 40 feet high. The width varied, but most were very thick. They ranged from 7 feet thick at Conisbrough Castle to 20 feet thick at Chepstow Castle. Dover Castle walls were 20 feet thick, while Duffield Castle walls were 18 feet thick.Hans Thalhofer 1459