Believe me, I’m as surprised as you to be using “beautiful” and “Halo” in the same sentence, but when looking at some of these screenshots, there’s really no other way to describe them.
A while back I did a gallery of humorous stills from the game, but this time around I went down the artistic route. Most of these images are probably good to go as desktop wallpaper, and you can click on any of them to see a bigger version.
I suggest you listen to something suitably epic as you look through these. Might I suggest this?