Fyrisån (Swedish pronunciation: [ˈfŷːrɪsˌoːn], "the Fyris river") is a river in the Swedish province of Uppland, which passes through the city of Uppsala and ends in Lake Mälaren. The "Sala" river in Uppland was changed in the 17th century in memory of the Fyrisvellir battle, mentioned in the Icelandic sagas, as it was the belief that the marshy plains called "Föret" was the site of the famous Battle of Fýrisvellir in the late 10th century.