Summer Olympic Games demand for tickets to all levels of each event, there was controversy when seats set aside for sponsors and National Delegations went unused in the early days. A system of reallocation was put in place so the empty seats were filled throughout the Games. Rio de Janeiro, Brazil hosted the 2016 Summer Olympics, becoming the third city in the Southern Hemisphere to host the Olympic Games after Melbourne, Australia, in 1956 and Sydney, Australia, in 2000, and the first South American city to host the Olympics. The preparation for these Games was overshadowed by controversies, including the instability of Brazil's
Doping at the Olympic Games effort to detect banned substances and recent blood transfusions. While several athletes were barred from competition by their National Olympic Committees prior to the Games, six athletes failed drug tests while in competition in Beijing. What follows is a list of all the athletes that have tested positive for a banned substance either during or after an Olympic Games in which they competed. Any medals listed were revoked by the International Olympic Commission (IOC). In 1967 the IOC banned the use of performance-enhancing drugs, instituted a Medical Commission, and created a list of banned substances. Mandatory testing began at the