Dechreuwyd adeiladu Castell Fflint ym 1277, un o’r cestyll cyntaf i gael eu hadeiladu yng Nghymru gan Edward I.  Aeth y Brenin yn ei flaen i adeiladu cestyll Biwmares, Conwy, Caernarfon a Harlech yng ngogledd Cymru, sydd heddiw’n ffurfio Safle Treftadaeth y Byd UNESCO.
Begun in 1277, Flint was one of the first castles to be built in Wales by Edward I. The King later moved on to construct the north Wales castles of Beaumaris, Conwy, Caernarfon and Harlech, which today form a UNESCO World Heritage Site.