Named for local banker and philanthropist Philip S. Miller, who in 1987 retired the debt on the former library on Plum Creek Boulevard with a single check. The current Philip S. Miller Library on Wilcox Street in downtown Castle Rock was once a grocery store. The building, redesigned by Humphries Poli Architects, opened in 2003. The library is also home to the Douglas County History Research Center and the library district's administrative and support services staff.