Urban planning and big events, such as the Olympic Games and Universal Expositions, are complementary. Big events promote urban planning, and often cause it to evolve. Urban development by Napoleon III and successive Universal Expositions led Paris to become a fashionable global center. The 2012 Summer Olympic and Paralympic Games in London contributed to gentrifying the London Docklands and the neighboring East End. The 1964 Summer Olympic Games in Tokyo also led to modernization of urban infrastructures and celebrated Japan’s revitalization and progress after the Second World War. However, the 1964 Olympic Games left some bad legacies, including damage to the historical landscape around Nihon-bashi bridge by an expressway. Now, as we prepare to hold the 2020 Summer Olympic and Paralympic Games in Tokyo, we should think not only about the events but also urban planning at the Tokyo Waterfront, where the main facilities are to be built. This paper presents the relationship of between urban planning and big events in modern history, and discusses implications and possibilities.