Scottish forest that is the location of Arthur's seventh battle in the Historia Brittonum by Nennius where Arthur fought the Picts and the Angles.
Also known as Cat Coit Celidon, this is the modern day Caledonian Wood which at one time covered most of Selkirkshire and Dumfries and ran over the highlands around the upper Clyde and Tweed rivers.
Celidon is also the location of the mad, prophetic wanderings of Lailoken, the "Wild Man of the Woods," driven insane by the Battle of Arfderydd in Cumbria. Known in the Welsh tradition as Myrddin, he wanders these woods for fifty years.
Myrddin later became known as Merlin.
Celidon is also the name of one of the domains in Kingdoms of Camelot.