Annwn is a Welsh term that refers to the Otherworld, a mystical place of peace and beauty that lies beyond the physical realm. Synonyms for Annwn include Elysium, the Celtic Otherworld, Avalon, the Isle of the Blessed, the Land of the Young, and Tir na nÓg. In Welsh mythology, Annwn was ruled by the god Arawn and was said to be the place where the dead went to be reborn or to find respite from the struggles of the mortal world. The concept of the Otherworld has appeared in many cultures throughout history and remains a prominent theme in literature and art.