PurposeSince the 1960s, the impact of mega sporting events on the built environment has become increasingly important, and the relationship between hosting cities and events increasingly complex and controversial. The outcomes of these mega-events, however, are very discouraging, especially in terms of the state of sports venues and event sites. In many cases, Olympic parks and event sites stand abandoned once the event is over, and sports facilities are often either closed or underutilized. The purpose of this paper is to identify replicable best practices and successful examples used in mega-events to transform events sites and venues into livable public open spaces (POS), enjoyed by the local communities.Design/methodology/approachThree cities were selected for this investigation: London, Sochi and Rio de Janeiro. London hosted the 2012 Summer Olympics, and this study focused particularly on its Olympic park, Queen Elizabeth Park. Sochi hosted the 2014 Winter Olympics but also some of the matches of the 2018 FIFA World Cup. Rio de Janeiro hosted the 2016 Summer Olympics and also a part of the 2014 FIFA World Cup. Each case was investigated according to a methodology composed of interviews with experts, site visits, and analysis of the bidding book and post-event reports to check the consistency between promises and legacies.FindingsThe research identified a framework of six major elements that determine, or contrast, the long-term use of events sites and sport facilities, and highlighted some main attributes to consider in order to transform sporting event sites into livable and enjoyable open spaces. It is expected that this framework can be used as a guidance to deliver sustainable events and long-term legacies and to define a strategy for optimization of planning mega sport events.Practical implicationsMega events provide near-unique, fast track opportunities for urban transformation. This research can be used as guidance for the overall mega sporting events stakeholders, such as the IOC, FIFA, and local organizing committees, to identify replicable best practices and successful examples in the leverage of mega events to transform events sites and venues into livable POS.Originality/valueWhy is it so difficult to transform event sites and sport venues into livable areas of cities? What are the recurrent mistakes, issues, and challenges that hosting cities have to face? This research is unique as it aims at answering these questions by defining a framework of relevant factors for hosting cities to help them in the planning of mega sporting events. The research also highlighted some recurrent mistakes, such as the exorbitant costs of a mega event, the inability to keep the initial budget unchanged and the difficulty to adjust plans to local needs.