The scale of human being is the most fundamental reference for city and architectural design. However, with the development of economy and urbanization, the way of living and thinking have changed. Consequently, mega-cities and ultra-high-rise buildings have come into being, which gradually reduces user-friendly space to an unreachable concept. In addition to physical scale, the psychological spatial scale of people is gaining increasing importance. In today’s Cool Chat, we invited industry professionals, experts and scholars in urban planning and architectural design to give people a new light on understanding city and architecture scale.