CNN posed the question to people in seven cities . Questions ranged from fire , to the written word , the Internet , and travel . A few people nominated the moon landing as man 's greatest achievement . Have your say through Sound Off , or send us a link to iReport .
CNN posed the question to people in seven cities . Answers ranged from fire , to the written word , the Internet , plane travel . A few people nominated the moon landing as man 's greatest feat . Have your say through Sound Off , or send us a video to iReport .