He built a second line of defence, raised the height of the Norman walls and erected a massive rectangular tower now known, not surprisingly, as Marshal’s Tower.
Adeiladodd ail linell amddiffyn, cododd uchder y waliau Normanaidd a chododd dŵr petryalog enfawr a elwir erbyn hyn, wrth reswm, Tŵr Marshal.