Cognition and social values prevail in urban evolution. Analysis of these values reconstruct an era that has largely vanished; the context is historic downtown Tucson, and the significance is the Mexican enclave that had La Placita as its social focus. The historical evolution and the urban character of La Placita and its surrounding barrio is documented with emphasis on the social meaning of its change. A newly developed cognitive theory of vantages and coordinates provides a model to depict the viewpoints that defined urban development in Tucson. The analysis of personal viewpoint provides a statement of the manner that social values and cognition shaped architecture and urban change throughout the years of growth in the center of Tucson.