Criccieth Castle was built around 1230AD by Llywelyn the Great. Unusually, there was no earlier earth and timber fortification at the site, and Criccieth appears to have been previously uninhabited. The first phase of construction created an inner ward, protected by a twin-towered gateway. The towers of the gateway provided the castle's accommodation.

Around 1260AD, Llywelyn ap Gruffudd added an outer ward and second gateway, with two large rectangular towers.

In 1283AD, Criccieth Castle was seized by English forces during Edward I's second Welsh campaign. Under the stewardship of James of St. George, an extra storey was added to the gatehouse, and an outer barbican was added to the curtain wall.

In 1294AD, Madoc ap Llywelyn led an uprising against the English. Criccieth was besieged throughout the winter, but survived until spring when the castle was resupplied.

In 1404AD, Owain Glyndŵr's forces seized Criccieth, and the Welsh tore down the castle's walls and torched its buildings. This marked the end of the castle's brief life, and it was never restored following this event.

Although the castle ruins look spectacular from a distance, surprisingly little remains upon closer inspection. Nevertheless, perched dramatically on a promontory facing out to the sea, the castle's position affords it a stunning setting. The views from the ruins are equally impressive, with Harlech Castle being visible to the south east on the far side of Tremadog Bay, flanked by the Rhinog mountain range in the distance.