Uncharted 3 didn't just pop out of Naughty Dog's studio, polished and fully formed, without any work from the developers themselves. Part of that "work" process involves pitching and sometimes discarding a level idea or two -- or 12. Naughty Dog has released a dozen images of the Uncharted 3 that could have been, along with a brief description of each, to IGN.
One canceled level is the "Foggy Forest," pictured above, which transformed into the French Chateau setting in the final game, with less mist and early-morning light. "The Sand Pit" had Sandlantis hidden in a desert sinkhole and the "Floating Reservoir" would have seen Drake fight his way up the inside of an oil reservoir in the shipyard.
Check out all of the would-have-been, could-have-been ideas here.