The world-renowned "Hesse-Sammlung Martin Pfeifer" housed on the top floor of the head office of Sparkasse Pforzheim Calw comprises a total of some 5,000 works. The co-founder of the International Hesse Colloquia in Calw began assembling the archive materials in 1948. Pfeifer's study library, which was acquired by Sparkasse Pforzheim Calw following the death of the collector in 1994, contains not only books - among them many first editions - but also other bibliophile gems such as private prints, poems, and copies of letters. Additionally, there is a wealth of notes and secondary literature, as well as bibliographies. Martin Pfeifer's three-volume international history of the reception of Hesse, Hermann Hesses weltweite Wirkung, and his "Hesse-Kommentar zu sämtlichen Werken" also form part of the collection. Storage of the exhibits under constant-climate conditions the whole year round necessitated the installation of a system featuring sophisticated, state-of-the-art technology. Arguably unrivalled anywhere else in the world, the Hesse Collection in the Pfeifer Archive at the Sparkasse is available for research purposes on request.