The monastery was dedicated to Saints Arsatius, whose relics were here, and Quirinus, whose relics were at Tegernsee Abbey, founded by the same brothers, to which Ilmmünster was affiliated.
His library can at least partially be reconstructed: Archimedes, Euclid, Plato, Paul of Alexandria, Theon of Alexandria, Proclus, Porphyry, Apollonius of Perga, the lost Mechanics of Quirinus and Marcellus, and possibly Thucydides.
Malmedy had been a branch of Stavelot, but between 1065 and 1071 became independent from this monastery.
Tombs from the 8th century BC to the 7th century BC that confirm a likely presence of a Sabine settlement area have been discovered; on the hill, there was the tomb of Quirinus, which Lucius Papirius Cursor transformed into a temple for his triumph after the third Samnite war.