The concept art of Nicolas “Sparth” Bouvier of 343 is just incredible. Everytime he posts new stuff, I’m compelled to post it here.
Here is the latest batch of concepts. These being some of the first he ever did for Halo 4.
This piece is exquisite in detail for a concept piece. Excellent contrast in dark and light with a well defined focal point in the blue engine exhaust. 
Is this an early concept of the Didact’s Cryptum?
A heavy industrialized look here. This seems to be a prominent structure of the UNSC.
And finally a fantastic concept of the cryo chamber room from the beginning of the Halo 4 campaign.
-Sal