The International Olympic Committee (IOC) will choose the winning host city on Oct. 2 in Copenhagen, Denmark

winning host city This combo photo shows the skylines of candidate host cities for the 2016 Summer Olympics, clockwise from top left, Chicago, Illinois, U.S.; Madrid, Spain; Tokyo, Japan; and Rio de Janeiro, Brazil, on various dates in September 2009. The International Olympic Committee (IOC) will choose the winning host city on Oct. 2 in Copenhagen, Denmark.