The Making of The Avengers - Concept Art
See even more stunning concept art for the Helicarrier, massive sets, and battle damage at Nathan Schroeder's portfolio site. I shared some of his gorgeous Captain America concept art previously. He also worked on Thor, several of the X-Men films, as well as many other major non-Marvel films - so I highly recommend spending some time looking around his site. Via Kotaku. Also Io9 has a really great article with production designer James Chinlund and concept artist Ryan Meinerding describing much of thought behind the design choices on everything from costumes to architecture here.