National Archives Museum

The Rotunda of the National Archives displays the original Declaration of Independence, the Constitution and the Bill of Rights in sealed, dimly lit cases, guarded around the clock. Seeing the actual 1776 parchment with the signatures is a short but memorable stop, and the surrounding galleries show a 1297 copy of Magna Carta and rotating documents from the vaults. The 1935 building on Constitution Avenue is a temple-fronted monument in itself, familiar from National Treasure. Free; timed-entry reservations are recommended in summer to skip the line, which can otherwise exceed an hour. Allow 45 minutes.