Hyperion, by Friedrich Hölderlin. Hölderlin's only completed novel — a passionate epistolary book about a young Greek's struggle for freedom — was begun and partly written in Tübingen. Reading it before climbing to the Hölderlinturm makes the visit far more affecting.
Phenomenology of Spirit, by Georg Wilhelm Friedrich Hegel. Heavy going, but Hegel began the work in his Tübingen seminary years and the town remains saturated in the German philosophical idealism he, Schelling and Hölderlin shaped together.
Diaries 1942–54, by Max Frisch. The Swiss novelist spent extended periods in Tübingen and used it as the setting for parts of his fiction; the diaries give a quietly observed picture of the post-war town.