The only “secret” room in the basilica is in the westwork. It was probably planned and built as a hiding place in the 17th century.
During wartime, the precious colored glass panes of the cloister, which depict the story of salvation from the fall of the angels to the resurrection, were hidden from looters in specially designed wooden boxes.
In 1785 the glass panes of the cloister were sold to England. Today a larger number of them are kept in the Victoria and Albert Museum in London.
Access to the Michaeliskapelle is not public.