2004 Summer Olympics return of the games to the city where they began. Having previously hosted the Summer Olympic Games in 1896, Athens became one of only four cities to have hosted the Summer Games on two separate occasions (together with Paris, London and Los Angeles). A new medal obverse was introduced at these Games, replacing the design by Giuseppe Cassioli that had been used since the 1928 Games. This rectified the long lasting mistake of using a depiction of the Roman Colosseum rather than a Greek venue. The new design features the Panathenaic Stadium. The 2004 Summer Games were hailed as "unforgettable,
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