Caer Cadarn was the stone-walled fortress of King Smoit and the seat of power to Cantrev Cadiffor, in the southern Valley Cantrevs of Prydain. Often a site of feasting and celebration, with its hewn stone walls and iron-studded gate, the castle was well capable of holding its own against an invading army.
Its gates and walls -- like the brows of its lord and master -- were dented and battle-scarred. The castle was situated on an open plain wooded with sparse thickets.
After the events of Taran Wanderer, Smoit bricked up the castle's dungeons, declaring them useless; during the events of The High King, when he was briefly ousted by the sinister Magg, Smoit -- along with several of the Companions, including Taran -- was held prisoner there in his own empty larder.