This essay explores urban street functionality and the concept of "street death," focusing on the Corbusier-Jacobs debate about the role of streets in cities. Corbusier prioritizes efficient traffic-oriented streets, while Jacobs emphasizes mixed-use streets for urban vibrancy. The study critiques Koolhaas' view on streets in vertical development and delves into Corbusier's city function concentration and Jacobs' mixed-use concept. Using Queen Street in Cardiff as a case study, we discuss its benefits like diversity and vitality, and challenges like congestion and safety. This case illustrates the interaction between the two perspectives. Overall, the essay underscores rational analysis for balanced functions, local needs, urban quality, and economic progress. Street diversity is crucial for dynamic spaces, improved experiences, and economic growth.