Since its origins in Ancient Greece, the Olympic Games are still the world's most important sporting event. It has been probably the one that influences both ancient and modern world. Apart from being the world's largest sporting event, the current Olympic Games are also seen as an important catalyst for urban change. Although Games are lasting for short periods, they are having long term consequences for the host city in terms of urban transformation, urban renewal and urban infrastructure. The aim of this paper is to structure a research on cities which have hosted Olympic Games by benchmarking based on legacy mainly in urban planning, sport and transportation infrastructure, urban landscape and regeneration. The features of the location of the event, pre-existing land uses, post event. Its legacy and its impact on urban structure and urban ecology of the host city will be analyzed and compared for four cases. These cases are Barcelona, Sydney, Beijing and London which have praised for their urban regeneration, urban renewal and urban sustainability fields after 1990's.