This chapter offers selective readings of some of the ideals and concrete urban reforms that transformed the city in the twentieth century since Pereira Passos' reform of 1902-1906 until the recent projects for the Porto Maravilha and the Olympic venues. It stresses how the imaginaries of the city shifted from the predominance of cultural inventions of the lettered city at the beginning of the twentieth century to the representations and expressions of the contemporary audio-visual metropolis. The discrepancies between the ideals of what the city should be and how it was perceived to be also permeated the imaginaries of Rio de Janeiro. In the late 1960s, Lucio Costa, the urban planner of Brasília, was called upon by the municipality of Rio de Janeiro to envision a blueprint for the Barra da Tijuca. For the embellished Rio of the Tropical Belle Époque, the menace behind the eclectically styled façades was the contagion and dissolution of European civility by the dangerous classes.