2020 Olympics: Six cities enter bids for Summer Games
Rome and Tokyo have hosted the Olympics before. Each of the other contenders have previously submitted bids.
Madrid is bidding for a third consecutive time. Tokyo, Doha and Baku are making their second consecutive attempts. Istanbul submitted its fifth overall bid.
The IOC will select the host city by secret ballot on Sept. 7, 2013.
-- Melissa Rohlin
Photo: Muhammad Ali lights the Olympic Torch at the Summer Games in Atlanta in 2001. Credit: Curtis Compton / AFP.