The story
It originated in the 15th century as a town library and can be dated back to 1484. After the founding of the university (1914) it became the Stadt- und Universitätsbibliothek Frankfurt am Main (StUB). In 1945, the libraries Stadtbibliothek, Rothschild'sche Bibliothek, Bibliothek für Kunst und Technik, Medizinische Zentralbibliothek, Manskopf'sches Museum für Musik- und Theatergeschichte merged. In 2005 the StUB and the Senckenbergische Bibliothek united.
From Wikipedia’s article on Frankfurt University Library, shared under CC BY-SA 4.0.4