The planned 2012 Summer Olympics will make London the first city to have hosted the modern Games of three Olympiads.
The 1908 Summer Olympics (the Games of the IV Olympiad) were the fourth modern Olympic Games and the third to be hosted outside of Athens, Greece. The International Olympic Committee considers them the fourth Olympic Games, discounting the intercalated 1906 Summer Olympics.
The 1944 Summer Olympics (Games of the XIII Olympiad) were scheduled to be held in London. Awarded in 1939, they were, however, cancelled due to World War II.
The 1948 Summer Olympics (the Games of the XIV Olympiad) were the first to be held after World War II, with the 1944 Summer Olympics having been cancelled due to the war.