Mexico City, Mexico hosted the 1968 Summer Olympics.
London hosted the Olympic Games in 1908 and 1948, and is now hosting the 2012 Olympics.
Seoul hosted the 1988 Summer Olympic games.
Athens
Montreal
Sydney, Australia was the host city for the 2000 Summer Olympics.
Paris, France.
Tokyo
Barcelona
Barcelona.
There was no Summer Olympics in 1966. 1964 was hosted by Tokyo, Japan and 1968 games were hosted by Mexico City, Mexico.
The first time the Summer Olympics were in London was in 1908. The second time was in 1948. London is the only city to have hosted the modern Summer Olympics three times, and the United Kingdom is one of only two countries that has hosted more than two modern Summer Olympics to date (the other is the United States, which has hosted four).