The document summarizes four reaction papers written by a student on theories of architecture and urbanism. The first paper discusses Louis Wirth's theory that density and diversity are defining characteristics of cities in addition to population size. The second paper examines the idea that architecture can generate memories and identity through experiential qualities. The third paper argues that memory is embodied and architecture can preserve history by generating new experiences. The fourth paper analyzes Kenneth Frampton's theory of critical regionalism and the importance of responding to context and user experience.