Chapter 16 of Earthopolis: A Biography of Our Urban Planet explores cities’ role as creators and creations of their own majority populations during the industrial Urban Planetary acceleration of the nineteenth century. Millions of new urban industrial workers and colonial subjects profoundly shaped cities by means of their own massive, often very-long-distance migrations; their grueling, often indentured and semi-servile labor; their construction and habitation of new housing; and their multifarious forms of political activism. The chapter examines the built structures and the associated political contests required for movement, changes in home life, factory work, associational life, and street protest. Urban political institutions also changed amidst a radicalization of revolutionary movements exemplified by the Paris Commune of 1871 and massive strike waves that followed everywhere on the Urban Planet at the turn of the twentieth century.