Letchworth Garden City, England, and the Falkenberg Estate in Berlin, Germany are two of the most influential relics of the Garden City Movement. Both have achieved heritage status for their impact in the field of urban planning, having offered logical and humanitarian solutions to the smoggy and overcrowded living conditions of the late 19th century caused by rapid, uncontrolled growth and densification of cities during the First and Second Industrial Revolutions. This heritage status restricts aesthetic and structural modification of the built environment with the goal of preserving the historic identity of the sites. Although deserving of historical preservation and recognition, Letchworth and Falkenberg continue to face the challenge of providing housing to future generations of residents. This paper argues that the monumentalization of the Garden City Movement heightens the tension between tradition (marked by static architectural preservation) and innovation (serving the evolving needs of the residents) at Letchworth Garden City and the Falkenberg Estate; it does so using a Rieglian understanding of monument preservation and a thematic analysis of the Letchworth Garden City Heritage Foundation and the Berliner Bau- und Wohnungsgenossenschaft von 1892, the two landowning organizations responsible for the stewardship and heritage preservation practices at each site. Using historical and contemporary primary and secondary sources and expert interviews, I show that both organizations resist the oppositional forces of tradition and innovation by bringing them into conversation with each other through new applications of the garden city model.