One-hour tours begin approximately every 20 minutes. D.C. Tours daily 10 a.m. to 1 p.m. Library of Congress First Street and Independence Ave. Video program every 30 minutes. National Zoo 3001 Connecticut Ave.
Admission is free, fee for parking.
The Pentagon Arlington, Virginia. Headquarters of the U.S. Department of Defense. Tours last 90 minutes. Metro - Pentagon . U.S. Supreme Court First Street and Maryland Ave.