Herringbone masonry is visible in places and the well-preserved gatehouse is almost certainly a relic of the Conqueror's time. Two triangular-headed windows above the blocked outer archway and another facing the bailey indicate its antiquity. They suggest Anglo-Saxon work, the only plausible explanation being that English masons were employed and continued to build in their traditional style.

The short barbican, with its tall arch, is contemporary with the rest of the gatehouse and thus the oldest in England. Exeter is one of those early Norman castles which put the emphasis upon a strong gatehouse instead of a keep.