Chapter 13 of Earthopolis: A Biography of Our Urban Planet explores cities’ role as creators and creations of nineteenth-century imperialism in all of its forms. It shows how imperial rivalries between London, Paris, and Washington DC, the three most “liberal” capitals on Earth, led imperialists to invest in “gun cities,” where arms manufacturers used coal-fueled technologies to produce new guns, cannons, and battleships that ended the “Age of Parity” between the gunpowder empires of Afro-Eurasia. The city of Calcutta served as the pivot-point of the new era of European dominance, serving as headquarters of the British conquest of India, and later as key port to undermine the power of the Qing Dynasty in Beijing by means of shipments of opium into Guangzhou (Canton) that resulted in European “concessions” in key ports of East Asia. The chapter also demonstrates how the settler colonial conquest of the Americas relied upon and resulted in the proliferation of new cities across the continent. Finally it shows how the imperial Scramble for Africa relied on all of these city-enabled techniques. In most cases, European imperial officials deemed some form of segregation by “race” crucial to the effectiveness of their urban weapons of conquest and imperial rule.