In Norse mythology, Mímisbrunnr (Old Norse "Mímir's well") is a well associated with the being Mímir, located beneath the world tree Yggdrasil. Mímisbrunnr is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson. The well is located beneath one of three roots of the world tree Yggdrasil, a root that passes into the Jötunheimr where the primordial plane of Ginnungagap once existed. In addition, the Prose Edda relates that the water of the well contains much wisdom, and that Odin sacrificed one of his eyes to the well in exchange for a drink. In the Prose Edda, Mímisbrunnr is mentioned as one of three wells existing beneath three roots of Yggdrasil, the other two being Hvergelmir, located beneath a root in Niflheim, and Urðarbrunnr.