It was founded in 1202 by Leopold VI, Duke of Austria and Styria, as a daughter house of Heiligenkreuz Abbey. Successive abbots acted as councillors to the rulers of Austria, and the abbey became wealthy as a result of this valuable connection. Abbot Matthew Kollweis (1650–1695) turned the monastery into a fortress during the Turkish advance against Vienna in 1683, installing a garrison and giving shelter to a large number of fugitives. In 1976 Pope Paul VI declared the abbey church of Lilienfeld a "basilica minor".