The Altuna Runestone (Altunastenen), designated as U 1161 in the Rundata catalog, is a Viking memorial runestone adorned with images from Norse mythology. It is situated in Altuna, Uppland, Sweden.
The Altuna Runestone stands at a height of 1.95 meters (approximately 6 feet 5 inches) and was discovered in 1918 by a local historian within the wall of a chapel near its current location. In a time when the historical significance of runic stones was not widely recognized, they were often repurposed as construction materials for roads, bridges, walls, and buildings. Notably, the Altuna Runestone is one of the few surviving runic stones with exclusively pagan illustrations from Scandinavian mythology. Most surviving runestones were created in the 11th century after the Christianization of Sweden, often by individuals seeking to outwardly demonstrate their adherence to the new faith, leading to the inclusion of Christian inscriptions on many stones.
However, one side of the Altuna Runestone features illustrations that depict a legend found in the Hymiskviða of the Poetic Edda. This legend tells the story of the Norse god Thor's fishing expedition to capture Jörmungandr, the Midgard Serpent. Thor embarks on this journey with the Jotun (giant) Hymir, using the head of a bull as bait. During the course of the story, Thor hooks Jörmungandr, but the serpent either breaks free or, as described in the Gylfaginning section of the Prose Edda, the line is severed by Hymir. The Prose Edda adds a humorous detail that, while Thor was pulling the line with Jörmungandr on the hook, his feet went through the bottom of the boat.
The image on the Altuna Runestone does not include Hymir, possibly due to the stone's narrow shape. However, it prominently features Thor, his fishing line and gear, the serpent Jörmungandr, and notably, Thor's leg, which is shown piercing through the hull of the boat. This encounter between Thor and Jörmungandr appears to have been a popular motif in Scandinavian art, and similar scenes can be found on other runestones and artworks.
In addition to its mythological imagery, the runestone bears an inscription that suggests it commemorates the individuals Holmfaster and his son Arnfaster, who were likely victims of a burning, possibly in an act of arson during a feud. The use of the name element "fastr" in both Holmfaster and Arnfaster's names indicates a familial connection, as was a common practice in Scandinavian naming traditions.
The runic inscription on the Altuna Runestone is carved in the Pr3 style, also known as the Urnes style. This style is characterized by slender, stylized animals intertwined in narrow patterns. The animals typically have profiles with thin, almond-shaped eyes and upward-bent appendages on the nose and neck. The runic inscription is attributed to rune masters with the normalized names Frösten and Balle, possibly with the involvement of Livsten. Balle was active in southwestern Uppland and northern Södermanland in the latter half of the 11th century.