The stockade was soon replaced by a masonry curtain wall. The remains of this wall shows that it was bonded into the repaired city walls, but not the gatehouse, indicating that it was built from the former towards the latter. Another early enhancement was the construction of a protective barbican over the city side of the drawbridge. There is evidence that the castle was attacked before it was completed. This evidence is both physical, in the form of repairs to Athelstan's Tower; and documentary, in a report made by Orderic Vitalis of an attack made on Exeter in 1069.