The Dom cathedral of St. Peter in Trier was built from the remains of an older 4th century church on the site. It is the oldest cathedral in Germany. Its present structure, with six towers, was built in stages in the 11th, 12th and 13th centuries. The church has a triple naved choir. Inside are many priceless and ancient furnishings. The tomb of papal envoy Ivo can also be seen. He died in 1144. Most of the works of art and other artefacts are displayed in the nearby Diocesan Museum.