Begun in 1277 it was the first of the revolutionary concentric, or ‘walls within walls’, castles designed by master architect James of St George.
Dechreuwyd adeiladu yn 1277, a hwn oedd y cyntaf o'r cestyll consentrig chwyldroadol, neu’r cestyll ‘muriau o fewn muriau’, a gynlluniwyd gan y prif bensaer James of St George.