Begun in 1277, Rhuddlan was the second of King Edward I's great Welsh fortifications. A protected river dock forms one side of the defences of this concentrically planned castle, dominated by a distinctive diamond-shaped inner ward.

Rhuddlan Castle came under attack in the Welsh rising of 1294, and again in the Glyn Dwr rising of 1400, when the town was badly damaged but the castle held out. Rhuddlan was in Royalist hands during the Civil War, until forced to capitulate in 1646. In 1648 it was partially demolished to prevent its further use.

Sources:
http://www.castlewales.com/rhudln.html
http://cadw.wales.gov.uk/