Question: What city held the 1956 Summer Olympics where Robert O'Brien competed in sprint canoe?

full_context: Document 1: 1976 Summer Olympics: The 1976 Summer Olympics, officially called the Games of the XXI Olympiad (French: Les "XXIes olympiques d'été"), was an international multi-sport event in Montreal, Quebec, in 1976, and the first Olympic Games held in Canada. Montreal was awarded the rights to the 1976 Games on May 12, 1970, at the 69th IOC Session in Amsterdam, over the bids of Moscow and Los Angeles. It is so far the only Summer Olympic Games to be held in Canada. Calgary and Vancouver later hosted the Winter Olympic Games in 1988 and 2010, respectively.
Document 2: 1948 Summer Olympics medal table: The 1948 Summer Olympics (also known as the Games of the XIV Olympiad) was an international multi-sport event held from July 29 through August 14, 1948, in London, United Kingdom. It was the first Olympic Games to take place in twelve years, due to the Second World War (and was known informally as "The Austerity Games" - largely due to countries having to bring their own food due to shortages in Britain), with London being chosen as the host city in March 1946. London had previously hosted the 1908 Summer Olympics, and was due to have hosted the event in 1944. A record 59 nations were represented by 4,104 athletes, 3,714 men and 385 women, in 19 sport disciplines. Following the Second World War, Germany and Japan remained under military occupation and had not yet formed their National Olympic Committee, and so were not invited. The only major Axis power to take part in the Games was Italy. The Soviet Union also did not form a National Olympic Committee and was ineligible to be invited to compete. However, they did send observers and competed in the 1952 Summer Olympics. Following the threats of a boycott from Arab countries should an Israeli team fly their flag at the opening ceremony, the International Olympic Committee (IOC) excluded Israel from the Games on a technicality.
Document 3: Russell Dermond: Russell Charles "Chick" Dermond (December 31, 1936 in Fair Lawn, New Jersey – May 9, 2015) was an American sprint canoer who competed in the late 1950s and early 1960s. His early years were spent in the American Canoe Association as a flatwater racer and began in the wooden "peanut," which was the predecessor of modern kayaks and C boats. A many-time national champion, he competed in the 1956 and 1960 Olympics. At the 1956 Summer Olympics in Melbourne, he was eliminated in the heats of the K-2 1000 m event. Four years later in Rome, he was eliminated in the repechages of the K-1 4 × 500 m event. He attended as Team Manager in 1972 and later served on the U.S. Olympic Committee. He was very active in the ACA, serving in a number of governing positions including Sugar Island in the Thousand Islands and Lake Sebago in Harriman State Park.
Document 4: 2000 Summer Olympics: The 2000 Summer Olympic Games, officially known as the Games of the XXVII Olympiad and commonly known as Sydney 2000 or the Millennium Olympic Games/Games of the New Millennium, were an international multi-sport event which was held between 15 September and 1 October 2000 in Sydney, New South Wales, Australia. It was the second time that the Summer Olympics were held in Australia, and also the Southern Hemisphere, the first being in Melbourne, Victoria, in 1956.
Document 5: Robert O'Brien (canoeist): Robert O'Brien (born June 6, 1933) is an American sprint canoer who competed in the late 1950s and early 1960s. Competing in two Summer Olympics, he earned his best finish of 11th in the K-1 10000 m event at Melbourne in 1956.
Document 6: 1952 Summer Olympics: The 1952 Summer Olympics (Finnish: "Kesäolympialaiset 1952" ; Swedish: "Olympiska sommarspelen 1952" ), officially known as the Games of the XV Olympiad, were an international multi-sport event held in Helsinki, Finland, in 1952. Helsinki had been earlier selected to host the 1940 Summer Olympics, which were cancelled due to World War II. It is the northernmost city at which a summer Olympic Games have been held. These were the first games to be held in a non-Indo-European language speaking country. It was also the Olympic Games at which the most number of world records were broken until surpassed by the 2008 Summer Olympics in Beijing. The Soviet Union, the People's Republic of China, Indonesia, Israel, Thailand, and Saarland made their Olympic debuts in Helsinki 1952.
Document 7: Song Soon-chun: Song competed for South Korea in the 1956 Summer Olympics held in Melbourne, Australia. In the bantamweight boxing event, he captured the silver medal. His silver medal was South Korea's first silver medal at the Olympic Games.
Document 8: Equestrian at the 1968 Summer Olympics: Equestrian competitions at the 1968 Summer Olympics in Mexico City, Mexico featured team and individual competitions in show jumping, eventing, and dressage. Mexico City proved a challenging site since it was 2,300 meters above sea level, resulting in 30% less oxygen in the air. The horses at the 1955 Pan American Games, which was also held in Mexico City, arrived a few weeks before the Games to adjust, but had difficulty in the competition. However, racehorses that competed at the same location and who were shipped in the day before, and left the day after the race, performed fine. It was discovered that although horses would adjust immediately to the high altitude during the first few days after arrival, they showed weakness and decreased performance around Day 10, which continued to Day 20. Therefore, nations were advised to ship in horses 3–4 weeks before the competition, which would allow them time to recover from the long travel, as well as adjust to the difference in altitude. Argentina, Ireland, and the USSR were the first to ship horses over, who arrived mid-September. France and Germany were the last countries to send their horses, who arrived 28 September, 20 days before the competition was to start.
Document 9: Venues of the 2000 Summer Olympics: For the 2000 Summer Olympics, a total of thirty sports venues were used. After Melbourne hosted the 1956 Summer Olympics, Australia made several bids for the Summer Olympics before finally winning the 2000 Summer Olympics by two votes over Beijing, China. Venue construction was set at the Homebush Bay area of Sydney in an effort to rehabilitate the land. Environmental studies of the area in the early 1990s forced remediation to be used for about a fifth of the site selected. Fifteen new venues were constructed for the Games. During the games, 137 cars were removed from the streets of Sydney before the start of the women's marathon while the last day of the canoe sprint finals were delayed by six hours due to heavy winds at the Regatta Centre. Many of the venues used for the 2000 Games continue to be in use as of 2017.
Document 10: Canoeing at the 1956 Summer Olympics: At the 1956 Summer Olympics in Melbourne, nine events in sprint canoe racing were contested. The program was unchanged from the previous two Games in 1948 and 1952. The competition was held on Lake Wendouree in Ballarat.
Document 11: Robbie Johnston: Robert ("Robbie") Ian Johnston (born 21 August 1967 in Balclutha) is a former long-distance runner from New Zealand who competed twice at the Summer Olympic Games and once at the Commonwealth Games. At the 1992 Summer Olympics in Barcelona he was ninth in his heat of the 5000m and did not advance to the final. At the 1996 Summer Olympics in Atlanta he was 12th in his heat of the 10000m and did not advance to the final. At the 1994 Commonwealth Games in Vancouver he did not finish the 10000m.
Document 12: 1956 Summer Olympics: The 1956 Summer Olympics, officially known as the Games of the XVI Olympiad, were an international multi-sport event which was held in Melbourne, Victoria, Australia, in 1956, apart from the equestrian events, which were held five months earlier in Stockholm. The 1956 Games were the first to be staged in the Southern Hemisphere and Oceania, as well as the first to be held outside Europe and North America. Melbourne is the southernmost city to host the games. Equestrian events could not be held in Australia due to quarantine regulations. This was the second Olympics not to be held entirely in one country, the first being the 1920 Summer Olympics, which Antwerp, Belgium, co-hosted with Amsterdam and Ostend.
Document 13: Robert Bruce (swimmer): Robert Bruce (born 11 March 1969) is an Australian former swimmer who competed in the 1988 Summer Olympics in Seoul, South Korea. As a 19-year-old, Bruce finished sixth in the final of the 200-metre individual medley, and third in the B final of the 400-metre individual medley.
Document 14: List of Olympic venues in sailing: For the Summer Olympics, there are 32 venues that have been or will be used for sailing. Most competitions took place for the early part of the Olympics at or near venues, but no specific yacht or sailing club was listed in the official Olympic report. In 1920, the twelve-foot dinghy event set for Ostend was moved to the Netherlands at special request of the Belgian Olympic Committee. The first specific yacht or sailing club to host the competitions took place in 1968 Summer Olympics in Mexico City though those competitions took place actually in Acapulco. Eight years later in Montreal, the competitions took place on the Great Lakes in Kingston, Ontario, marking the first and only time the sailing competitions took place in freshwater.
Document 15: Bobbie van de Graaf: Robert "Bobbie" van de Graaf (born 17 March 1944) is a retired Dutch rower who won a bronze medal in the coxed fours at the 1964 Summer Olympics. His team mates were Marius Klumperbeek (cox), Lex Mullink, Freek van de Graaff and Jan van de Graaff. The latter two were also born in 1944 and are unrelated to Bobbie.
ground_truth: Melbourne