It is a true Welsh castle, rather than a Norman or English one, and was built by Llywelyn ap Iorwerth, also known as Llywelyn the Great, Prince of Gwynedd in the early 13th century. According to local folklore a watchtower was constructed on the summit of Craig yr Aderyn and was used to warn the castle whenever danger approached. For more information on the castle, and Welsh castles in general see the excellent Castles of Wales website.