The motte was built partly over Anglo-Saxon burh wall, and the castle defences incorporated St George’s Tower, which had been part of the Anglo-Saxon west gate.
The Empress Matilda became trapped in Oxford Castle by Stephen’s forces in the winter of 1141. She finally escaped at night during a snowstorm, fleeing over the frozen river to Abingdon.
The photograph shows St George’s Tower.
See also: Oxford Castle and the Saxon Town Walls