Born in Solgne, Lorraine, he studied in Munich and assisted Theodor Fischer 1902–6 at the Technische Hochschule (Technical High School), Stuttgart, before himself becoming a professor in 1908. In partnership (1913–27) with Friedrich Eugen Scholer (1874–c.1949) he designed the City Hall, Hanover (1911–14), and the Hauptbahnhof (Main Railway Station), Stuttgart (1911–28), which owes something to Saarinen's great terminus at Helsinki as well as to the AEG buildings of Behrens. The partnership also designed locks, bridges, weirs, and other structures on the Neckar Canal (1926–36), the Graf Zeppelin Hotel, Stuttgart (1929–31), and many other buildings, including several private houses. Among Bonatz's other buildings the Henkel warehouses, Biebrich (1908–9), and the University Library, Tübingen (1910–12), may be cited. Later, Bonatz was consultant to Fritz Todt for the design of the Autobahnen (motorways) and their handsome bridges (1935–41). He was a signatory of the Block manifesto, and most of his domestic work was rooted in traditional forms. With Paul Schmitthenner (1884–1972) and Heinz Wetzel (1882–1945), Bonatz built up the Stuttgart School of Architecture as a bastion of traditionalism against the ferocious onslaught of International Modernism, and so it was no accident that the Weissenhofsiedlung was established at Stuttgart as a challenge and almost a declaration of war. The response of Bonatz and his colleagues, in collaboration with the local timber industry, was to build the Kochenhofsiedlung (1933—the name suggested basic realities (Kochen ‘cooking’) as opposed to the white impracticalities of the rival Siedlung (settlement, colony, or housing-estate) ), drawing on regional vernacular architecture, traditional timber construction, and craftsmanship, as a riposte to the alien imagery favoured by Mies van der Rohe and his associates.
Under National Socialism Bonatz prepared schemes for the Naval High Command (1939–43) as part of Speer's reordering of Berlin, and for the Hauptbahnhof in Munich (1939–42)—both unrealized. He also designed the War Memorial Chapel, Heilbronn (1930–6), the Stumm Company Building, Düsseldorf (1935—with F. E. Scholer), and the Kunstmuseum, Basel, Switzerland (1936). Disheartened by lack of recognition and by the dearth of building commissions during the 1939–45 war, he emigrated to Turkey in 1943, where he was appointed City Architect of Ankara, and became Professor at the Technical University, Istanbul, in 1946. The State Opera House, Ankara (1948), was erected to his designs. On his return to Stuttgart in 1953 he concentrated on repairing war-damage suffered by his earlier projects, published Leben und Bauen (Life and Buildings) in 1950, and worked on the reconstruction of the opera-house at Düssoldorf in the 1950s.
Bonatz (1950);Bongartz et al . (1977);Graupner (1931);Lane (1985);Lotus International, xlvii (1985), 70–91;Rittich (1938);Roser (1991)