he National Archives and Records Administration collects millions of documents, but you're probably familiar with at least two of them already: the Declaration of Independence and the Constitution. Between 2001 and 2003, these founding documents were painstakingly cleaned, repaired, and vacuum-sealed in state-of-the-art encasements to preserve them for posterity and make them easier to read. During the day, they're displayed in a neoclassical rotunda, and at night, they're locked in an underground vault for safekeeping. In the public vaults, visitors can research their genealogy, view original patent drawings (like the pencil), and listen to recordings of White House conversations during the Cuban Missile Crisis. Touring the exhibits takes approximately 90 minutes. Reservations are recommended (202-357-5450); otherwise, expect to wait an hour or more outside of the building.