The Essen cathedral treasure is considered the most important legacy of the Essen nunnery. Its abbesses ruled the convent and the city of Essen from the 9th century until around 1800.

The treasure includes works of art of inestimable value. Among them are valuable reliquaries, four Ottonian lecture crosses, a small crown that is considered the oldest lily crown in the world, and a magnificent sword with scabbard that is even associated with Emperor Otto the Great.

The most important work of art in the Ruhr region is the Golden Madonna, the oldest fully sculptured portrait of the Virgin Mary in the world. Dating from around 980 AD, the figure of Mary is still a highly venerated image of grace today and stands in the left aisle of Essen Cathedral. The seven-branched candelabrum also still has its place in the cathedral. It is the oldest surviving seven-branched candelabrum in Christendom and was cast in bronze around the year 1000.