The Welsh mountain where lives The Grey King. In coming here to recover, Will unintentionally encroaches upon this Lord's land, a place held within his grip for ages untold.
It is said that when the scrappy clouds blow about the crown of the mountain, it is the breath of the Brenin Llwyd, and it is always a sign of bad weather to come.
It is on this mountain that Bran and Will pass through Bird Rock ('the door of the birds where the breeze breaks') into an ancient place where only the High Magic rules.