This Element offers seven propositions toward a theory of 'Our Urban Planet' that is useful to global urban historians. I argue that historians have much to offer to theorists particularly those involved in debates over planetary urbanization theory and the Anthropocene. We must enlarge our concept of 'urban' to include spaces that make cities possible and that cities make possible and become comfortable with longer temporal frames that nest global urban history within Earth Time. Above all we need to add the crucial dimension of power, redefining cities as spaces that humans produce to amplify harvests of geo-solar energy and deploy human power within space and time. The element uses insights from 'deep history' to set the stage for a 'theory by verb' elaborating the many paradoxes of humans' 6,000-year gamble with the Urban Condition and explaining cities' own intrinsic capacity to outrun their own theorizability.

Capitalist private property in land and buildings – real estate – is the ground of modern cities, materially, politically, and economically. It is foundational to their development and core to much theoretical work on the urban environment. It is also a central, pressing matter of political contestation in contemporary cities. Yet it remains largely without a history. This Element examines the modern city as a propertied space, defining real estate as a technology of (dis)possession and using it to move across scales of analysis, from the local spatiality of particular built spaces to the networks of legal, political, and economic imperatives that constitute property and operate at national and international levels. This combination of territorial embeddedness with more wide-ranging institutional relationships charts a route to an urban history that allows the city to speak as a global agent and artefact without dispensing with the role of states and local circumstance.