Soiled and neglected industrial sites provide Smithson with an allegory to the city that is not as regulated. These structures are obviously of human creation and meant to perform a set of functions, much like a city is organized. However, these spaces differ drastically in that they are not meant for habitation. The human factor is left unconsidered, the priority of the structures being some industrial process that need not interact with humans except for their operators. Thus, these become realms of machines, expanses populated not by humans but by hulking masses of masonry and metal, blind to the human cities they surround and serve. Cities differ only in that the hunks of masonry are tuned to human interaction and as a result are molded and maintained by their constant visibility. A city must look the part up to the expectations of its inhabitants. It is a groomed space, organized and dressed up for show solely because of its constant audience. Industrial spaces lack the formality. They remain functional just as a city, but are just that, functional, not tied up in ribbon for constant display to a judgmental populace. Both spaces perform their service regardless of outward appearance, which upsets the superiority of cities to the industrial complexes that support them. If both spaces are working properly, why should the prim and proper city be any more important than the disheveled factory? This division stems from the visibility of the two sites, as a densely populated city is under constant scrutiny, industrial centers are kept out of sight and out of mind of the wider world, to the point of outsourcing to other countries. A desire for a clean beautiful city or pristine suburbs has created an unsustainable "not in my backyard" effect, where the consumers of industrial products are so distant from industry that they cannot know how or where things are manufactured. This hinders the improvement of industry, because it is near impossible to enforce labor or sustainability regulations from such a distance.