The Cross of Otto and Mathilde, Otto-Mathilda Cross, or First Cross of Mathilde (German: Otto-Mathilden-Kreuz) is a medieval crux gemmata (jewelled cross) processional cross in the Essen Cathedral Treasury. It was created in the late tenth century and was used on high holidays until recently. It is named after the two persons who appear on the enamel plaque below Christ: Otto I, Duke of Swabia and Bavaria and his sister, Mathilde, the abbess of the Essen Abbey. They were grandchildren of the emperor Otto I and favourites of their uncle, Otto II. The cross is one of the items which demonstrate the very close relationship between the Liudolfing royal house and Essen Abbey. Mathilde became Abbess of Essen in 973 and her brother died in 982, so the cross is assumed to have been made between those dates,[1] or a year or two later if it had a memorial function for Otto. Like other objects in Essen made under the patronage of Mathilde, the location of the goldsmith's workshop is uncertain, but as well as Essen itself, Cologne has often been suggested, and the enamel plaque may have been made separately in Trier.[2]