The nunnery was founded in 1004 by Adula or Adela of Leoben, wife of Count Aribo I, and her son, also called Aribo, the future Archbishop of Mainz, on the family's ancestral lands, and was settled by canonesses from Nonnberg Abbey in Salzburg. The first abbess was Kunigunde, sister of Archbishop Aribo. It was made an Imperial abbey by Henry IV in 1020. The Benedictine Rule was introduced in the 12th century.