St. Matthias‘ Abbey is a monastery in Trier (Treveris), Rhineland-Palatinate. The abbey has its roots in the mid-5th century, when it was built by Cyrillus, the bishop of Trier, to honor the founders of the archdiocese of Trier, Eucharius and Valerius. That is why the monastery was originally called St. Eucharius‘ Abbey. The bones of Eucharius and Valerius are being preserved in the monastery‘s crypt since the 10th century, and the monks adopted the Rule of Saint Benedict around the year 977. In the early 12th century, a new church building was constructed in the romanesque style. During the demolition of the old church buildings, the supposed bones of the apostle Matthias were found and are being preserved in a sarcophagus within the crypt. In the year 1148 the unfinished church was concecrated by Pope Eugene III. and several cardinals. From there on, the abbey turned into an important site of pilgrimage since it contains the only tomb of an apostle north of the Alps, and the abbey became increasingly known as St. Matthias‘ Abbey.