In the 10th century, emperor Otto I donated the monastery to the Prince-Bishopric of Liège in order to prevent local nobleman from seizing control of the property.
Shortly afterwards the nunnery was replaced by a collegiate chapter of (male) canons, who in the 12th century built the Romanesque church which partly survives in the present building.
The present church was partly built in the 12th century and consists of a 3-aisle basilica in Mosan style, without transepts.
The nave is the best preserved part of the original interior of the church, although the wooden ceiling was renewed in the 19th century.
The primitive red and ochre murals in the nave date from the 13th century and are among the oldest in Belgium.