In "The City: Suggestions for the Investigation of Human Behavior in the Urban Environment", Robert Ezra Park challenges the reader to understand the city beyond it's apparent physical morphology and to focus upon its human social behaviors. Park, writing in 1915, is credited with coining the term, "human ecology", to describe how human activity in the city as similar to how animal populations organize themselves in the wild...e.g. assimilation, adaptation, competition for limited resources, etc. Human ecology inevitably affects how spaces in the city become physically utilized and organized according to the invisible social forces.
Park goes on the analyze aspects of human behavior and psychology, how we respond to crises, power, social change, etc. and how that all relates to urbanism. The critique is broad (and somewhat tinged in overgeneralization ...like his passage about the Jewish populations), but I think what makes this text interesting aside from it's human ecological standpoint, is that poses many more questions to the reader than it answers. Park sees the the city is an organism, and it can be studied in a scientific way. Additionally, many of the issues addressed by Park are still relevant today.