Carndochan Castle was built between 1215 and 1230 by Llywelyn ap Iorwerth, otherwise known as Llywelyn Fawr. It is located in Gwynedd, two miles west of Llanuwchllyn.

We know very little about Carndochan, other than it was one of the many castles constructed by Llywelyn Fawr to oversee roads in Gwynedd and to protect his herds of cattle. Like Castell y Bere, which was built around the same time, it occupies a strong defensive position with steep crags on three sides. The area was strategically important dating back to Roman times. One fort, Caer Gai, lies beside the main road a mile north of Llanuwchllyn, and roads are thought to have converged on the fort from Bala, Brithdir, and Tomen-y-mur. 

The castle is described as ‘ruined’, and is basically a pile of rubble. At one time, it had a D-shaped tower, similar to Castell y Bere. Today, the one tower still standing is only 8 feet high.