The Cathedral, formerly the collegiate parish Church of Our Lady of Adoration, has remained unfinished. On the site of the current church once stood a 12th century Romanesque church which itself was preceded by two earlier churches. Construction of the choir of a new church began in 1230.
The building plans were changed a number of times, as is apparent when observing the variety of styles from early to late Gothic. After only partial completion of the splendid south tower and west facade, construction came to a halt due to lack of funds. Of the many stone carvings and statues planned for the outside walls, only a modest portion was completed. The Romanesque west front and north tower, known as the Heidenturm or “Heathen Tower,” were left standing and are an integral part of the current church structure.
Entrance to the church is through the early Gothic south portal. Very little of the original interior has survived other than the Romanesque font from the earlier church, a large, late 14th-century Pietá, two depictions of the Mother of God on a crescent moon and other figurines from the late Middle Ages. There are a number of interior details such as the pulpit and the Baroque tombstones which date from the time of the Imperial Chamber of Justice.
The church has been used concurrently by both Protestant and Catholic congregations since the Reformation.