The Rare Book & Manuscript Library at the University of Illinois is infested with mold and will be closed down for an $800,000 cleanup. Officials say 15,000 books in the collection are believed to have mold, but the number could be higher, because that includes only what's visible. The 300,000-piece collection occupies a self-contained vault inside the school's main library on the Urbana-Champaign campus and is worth more than $1 billion. It includes the papers of Carl Sandburg and H.G. Wells. An outside firm will undertake a painstaking cleanup of each item, as well as shelves, walls, floors and the ventilation system.