You only see what you know (Goethe)
The Marienbibliothek, a library named after the nearby church Marienkirche was founded by Sebastian Boetius in 1552. In the beginning, the books were stored in a tower of the Marienkirche. Today the library is housed in a typical magazine of the late 19th century with iron stairs and iron-cast pillars.
The library was founded by August Hermann Francke for the teachers and pupils at the schools of the Francke Foundations. With its opening in 1728, it is regarded as Germany’s oldest surviving secular library building. [German]
Fun! There is a public library inside a former phone box in Poysdorf. You can take some books for free without asking. You are only ought to bring them back or to put in some other books instead.
The Duchess Anna Amalia Library (Herzogin Anna Amalia Bibliothek) houses a major collection of German literature and historical documents. In 2004 a large part of the library became destroyed by a terrible fire. In the ground floor there is a worth seeing exhibition telling about how scientists rescued damaged documents.
Inside the municipal library (Stadtbibliothek) of Stuttgart. The library situated on the Mailänder Platz was planned by the Korean architect Eun Young Yi. I especially love the patterns of all these books inside the library.