The visitor center itself is worth a visit, as the structure is both functional, yet architecturally unique and beautifully blended into its forest environs. I don't know or remember much about its construction, history, or materials (I believe it has a copper roof), but will update this post if I come across more info.
Great birdwatching up here (many species of woodpeckers) in a tranquil setting of pines and manzanitas.
NOTE: Unfortunately, the devastating 2009 Station Fire may have prompted closures of the visitor center and/or some of the campsites. Be sure to check with the Forest Service district office for the latest conditions before heading out.
http://library.byways.org/assets/56431 (Chilao Visitor Center)
http://www.fs.usda.gov/detail/angeles/about-forest/?cid=stelprdb5162107 (U.S. Forest Service-Chilao Visitor Center)
http://www.forestcamping.com/dow/pacficsw/anginfo.htm (Chilao Campground)