The Pentagon Force Protection Agency protects and safeguards the occupants, visitors, and infrastructure of the Pentagon and other DoD-occupied property in the National Capital Region.
The embassy website provides a list of all foreign embassies in Washington D.C. and their contact information, as well as a list of those on Embassy Row.
The Washington Metro and Transit Authority website provides useful and helpful information to visitors and locals alike. It has maps, timetables, fare calculators, and many other useful tools to make "metroing it" an easy experience.
Both websites provide the necessary contact information for either your Senator or Congressman/woman, so they may be contacted to request a variety of tours, including the Pentagon, the White House, and the Capitol. For more information www.house.gov is for Congress and www.senate.gov is for the Senate.
This helpful website provides a plethora of information regarding historic sites, memorials, monuments, maps, and tours available in the Nation's Capital.