The article brings together the academic and industry literature on the design and management of urban airspace. We analyze the proposed airspace concepts, identify their strengths and weaknesses, point to gaps in research, and provide recommendations for a more holistic approach to designing urban airspace. We first identify the structural factors that define the size, capacity, and geometry of urban airspace. These factors are grouped into four categories: safety-related factors, social factors, system factors, and aircraft factors. Second, we review different urban airspace concepts...