My dissertation argues that in early 19th-century Paris, theories on physical and moral hygiene comprised a politically charged subtext in the transformation of spaces where gender and class identities were refashioned. At a time when political turmoil spurred fears over national decline, new architectural forms – such as gymnasiums, swimming pools, and public gardens – facilitated hygienic practices for rehabilitating French bodies. I trace the translation of these spatial practices across a range of settings, from the army and boys’ and girls’ schools to bourgeois leisure grounds, interrogating the role of architecture in shaping modern embodiments of gender, class, and citizenship.