OVER THE LAST THREE MILLENNIA our planet has been increasingly covered with buildings. Humans are not the only species to reconfigure their environments, but we are special in the speed and variety of means by which we have done so, and in the deliberation involved in the process. That last point is crucial, for there is no likelihood that snails forming their shells ‘deliberate’, and scant evidence that birds building their nests do. Even beavers constructing dams are likely to be genetically programmed to do so rather than consciously deciding. Although Christopher Wren thought that the ‘Project of Building is as natural to Mankind as to Birds’, people come from a stock, the great apes, with no tradition of this project. As a working hypothesis we might suppose that, though our capacity to build is inherent, our inclination to build is opportunistic and imitative. It involves making the most of available resources and learning from observation, including watching the activities of other animals. Critically, what the process has enabled is our colonization of territory where nature, especially the climate but also dangerous creatures, might otherwise have been too threatening to our safety. Ultimately it has enabled us to format our landscapes, socially and conceptually as well as materially, distinguishing civilization from wilderness, culture from nature.