The crypt of the collegiate church is a spacious hall crypt with rich architectural decoration. In addition to the tombs of the ruling couple, it contains a number of valuable abbess tombstones and unique late Romanesque vault paintings. The oldest tomb slabs were already created in the 1st half of the 12th century. They show the deceased imperial daughters who presided over the monastery as abbesses (including Beatrix I, daughter of Henry III) – as full-length figures and are thus among the oldest surviving full-length tombstones in Europe.