The town dates back to 852, when Gandersheim Abbey, a house of secular canonesses, was created in nearby Brunshausen by Liudolf, Duke of Saxony and his wife Oda. The first abbey church () in the town proper was begun in 856. In 990 the abbey received the market and tax rights. During the 10th century, Gandersheim was one of the most important towns of Saxony; the first German poet Hrosvit lived and worked here until 973. In 1159 Gandersheim was first mentioned as a town.