Decadent artists and writers in the second half of the nineteenth century were fascinated by the chaos and thrill of modern life, but they were to a much greater extent disgusted by the impact of so much social and cultural change. Baron Haussmann transformed Paris in the 1850s and 1860s into a booming metropolitan marvel, but in Les fleurs du mal (1857) Charles Baudelaire evokes the city as both spectacle and spectre. 350,000 people were displaced to the outskirts of the city during this period as new commercial sites replaced the medieval streets and alleyways. In this chapter, the development of the concept of decadence as a critique of urban progress is traced via Baudelaire’s foundational collection of poems and its influence on other writers, like Théophile Gautier, Émile Zola, and Joris-Karl Huysmans whose novel À rebours (1884) evokes the spiritual wasteland and psychological alienation that are the advance of modernity.