The southern chapel, the "Nikolauskapelle", has remained unchanged and retains its medieval aspect. Its traceried windows date from the 13th century. It displays Gothic stone sculptures under a baldachin (St. Catherine and St. Nicolaus) (1350) and a wooden crucifix by Hans Schlais (1510–1520). This chapel was founded by a cook of the duke at about 1350, giving thanks to the Lord for being acquitted of a poisoning case. The triumphal arch between the transept and the choir dates from the 14th century. Its spandrel is decorated with "The Last Judgment".