To prove to Europeans that America was cultured, John Adams plunked the world's largest library on Capitol Hill. The LOC's motivation is simple: 'universality,' the idea that all knowledge is useful. Stunning in scope and design, the building's baroque interior and neoclassical flourishes are set off by a Main Reading Room that looks like an ant colony constantly harvesting 29 million books. The visitor center and tours of the reading rooms are both located in the Jefferson Building, just behind the Capitol building.