This Element explores the history of urban planning, city building, and city life in the socialist world. It follows the global trajectories of architects, planners, and ideas about socialist urbanism developed during the twentieth century, while also highlighting features of everyday life in socialist cities. The Element opens with a section on the socialist city as it took shape first in the Soviet Union. Subsequent sections take a comparative and transnational approach to the history of socialist urbanism, tracing socialist city development in the Union of Soviet Socialist Republics (USSR), Eastern Europe, Asia, Africa, and Latin America.