The Beinecke Rare Book and Manuscript Library contains the principal rare books and literary manuscripts of Yale University and serves as a center for research by students, faculty, and other scholars. One of the largest buildings in the world devoted entirely to rare books and manuscripts, the library has room in the central tower for 180,000 volumes and in the underground book stacks for over 600,000 volumes; it now contains about 500,000 volumes and several million manuscripts. Temperature and humidity controls ensure that stored materials are protected for future generations. The white, gray-veined marble panes of the exterior filter light so that rare materials can be displayed without damage. Upon entering, visitors see the glass tower of books that rises through the core of the building. The Gutenberg Bible, the first Western book printed from movable type, and Audubon's Birds of America are on permanent exhibition. The library contains six major collections: the General Collection, which is administratively divided into the General Collection of Early Books and Manuscripts and the General Collection of Modern Books and Manuscripts; the Collection of American Literature; the Collection of Western Americana; the German Literature Collection; and the Osborn Collection of English Literary and Historical Manuscripts.