Sigfried Giedion (1888–1968), one of the main protagonists of the architectural avant-garde in Europe, paradoxically achieved this reputation in America, far from his homeland. Nearly all of Giedion’s books written after his initial stay at Harvard University were published in English long before they became available in his native German. Reto Geiser sheds new light on Giedion’s life and reassesses his work through the lens of cultural transformation and modernization processes. The author questions the unbroken line of developments portrayed in the historiography of modern architecture, and argues that Giedion’s position in between two cultural spheres not only caused ruptures and contradictions in his work but also productively shaped its reception on either side of the Atlantic.