Spontaneous orders are all around us. These have been defined as resulting from human action rather than human design. Prominent examples include language, th e common law, the scientific process, the various applications of the internet, and the market economy – all of them important contributors to our wealth and welfare. Yet we are also sur rounded by objects that are product s of human design. The list is to o long and too obvious to enumerate. In this essay, I will claim that cities are spontaneous orders. The theory has been well developed by Webster and Lai (2003) while the intuitions had been articulated by Jacobs in 1961 . I will discuss two challenges to this view: (1) considerable and numerous human design elements make up the city; and (2) there are schools of thought that maintain that cities are or should be all about human design. So in thinking about cities, what is the logical division of labor between spontaneous order and human design? Given the dispersed nature of specialized knowledge and discarding the unrealistic idea of idealized and all - knowing master planners, learning via trial - and - error experimentation and discovery is essential. Th is is most likely to occur at any scale for which private ownership is possible.