Sad somber song for a 9/11 tribute?

In school, we make video announcements. My group is doing a tribute to 9/11. I want to do, I guess, a montage would be a good word, of pictures and facts. I want a kind of sad, slow somber sad song. I don't want anything political. I'm not a connoisseur of music, so if you have an idea, that'd be perfect.