Here is the ArcSpace.com website page about the Ara Pacis Museum. This is an architecture based website, and the gist of this article is overall sympathetic to the project and the architect - it doesn't get into the Ara Pacis itself in any detail. It does have some good photos of the museum and architectural models, computer renderings, and elevation drawings though. If you are interested in the building, this site is a good reference and worth checking out.