Many of Washington, D.C.'s top attractions require waiting in line for admission tickets, especially in summer. To avoid the long lines, tourism experts recommend calling the museum or attraction in advance to ask about advanced tickets or pre-arranged tours. The International Spy Museum, for example, offers advance tickets through Ticketmaster. Another option is contacting your state's senator or representative well ahead of time for tickets or to arrange special tours. Tours of the White House must be prearranged through one's member of Congress.