Drawing on sociological approaches to urbanism and secularization, as well as the affective turn in anthropology, this article explores the implementation of secular policies in Iran after the 1936 Unveiling Decree. I argue that constructing transparent social relations reflects the emergence of a new level of secular binds and relies upon the modalities of urban infrastructure and architecture. I find that modernization and secularization in Iran are interlinked by transformations in urban planning that tended to eliminate sites of ambiguity and to homogenize structures and forms of interaction in public and domestic spaces. The article makes use of autobiographical narratives that give witness to manifest changes in the urban atmosphere between the 1930s and 1950s. I will show how the Pahlavi regime took an active role in attempting to build a secular city by invoking segmentations and divisions in urban spaces to promote a secular atmosphere and limit religious ideas.