Nowadays, our planet appears covered by a mesh of cities. Through mobile devices, automobiles, fashion, music, or eating habits, the "global city" seems to overlap largely with the notion of "global society". Actually, however, it is a little different. Cities are, first of all, dense congregations of people, where encounters of diversity take place. With the city as their stage, people of different cultural backgrounds connect and confer. Secondly, cities are concrete places composed of material buildings, roads, plazas, and vehicles. Urban planning and the city’s geographical structure thus condition all happenings in the city. Third, each city has its unique history, which shapes the individual cultural character of a city. Understanding the global city means to think about the concrete locale of a specific city that has developed as a gathering of diverse people, who are connected globally. That concrete city can be anywhere. Let's focus on the downtown area of the global city you are interested in. Using the developmental direction central Tokyo should take beyond the 2020 Olympic Games as a lens, we shall examine by comparison issues such as redevelopment, gentrification, cultural trends, the new creative and information industries, crime, and entertainment areas, old shopping streets and slow mobility and so forth.