The Gothic-style Petrikapelle, Chapel of St. Petri, was built in the 13th century on the site of a former castle chapel in front of the courtyard of the cathedral. After the removal of the Burgrave’s office by the Askan margraves, the chapel was handed over to the Bishop. It was converted into a parish church in the years 1314 to 1320.
The former narrow Gothic windows and the eastern gable end were completed during this conversion. The timber barrel vaulted ceiling was replaced in 1520 by the late-Gothic cell vaulted ceiling supported by pillars. Today the church premises are used for exhibitions of modern art.