Caer Dathyl

Caer Dathyl was a Welsh fortress in Arfon in northern Gwynedd referred to in the Fourth Branch of the Mabinogi (11th century), the Tale of Math fab Mathonwy. Its precise location is currently unknown and has been the subject of speculation. In the tale, it is the seat of Math's court to which Gwydion ap Don takes the hero Lleu Llaw Gyffes.