The world's largest library – with 164 million books, manuscripts, maps, photos, films and other items – awes in both scope and design. The centerpiece is the 1897 Jefferson Building. Gawk at the Great Hall, done up in stained glass, marble and mosaics of mythical characters, then seek out the Gutenberg Bible (c 1455), Thomas Jefferson's round library and the reading room viewing area. Free tours of the building take place between 10:30am and 3:30pm on the half-hour.

　　A groovy underground tunnel connects the library's Madison Building, where the Madison Cafe hides on the 6th floor and offers views of the city. Room 133 is where staff members issue library cards to anyone who wants to do research (or Room 139 in the Jefferson Building). A handy tunnel also runs to the Capitol Visitor Center.