Many sites in D.C. require tickets for entry. Some require them year-round and some require them only during the tourist season, primarily March - August. Most of these sites offer the opportunity to acquire tickets in advance for a small booking fee.
It is also sometimes possible to obtain tickets to some of these attractions through the office of your U.S. Representative or U.S. Senator.
1. White House Tours
2. U.S. Capitol Tours
3. Washington Monument:
The Washington Monument closed in Sepetember 2016 for repairs to the elevator. No date for re-opening has been announced.
4. Smithsonian's National Museum of African American History and Culture
Opening in September 2016, this is the newest of the Smithsonian museums and the only one to require tickets (free) for admission. Advance tickets through March 2017 have all been distributed. The date when advance tickets for April - June will be available will be announced on the museum's website. Based on past experience, these tickets will be snapped up within a day or two. A very limited number of same day tickets are distributed beginning at 9:15 am, but reportedly people are lining up for these tickets beginning at 6:00 am.
5. Ford's Theatre
Various combinations of access to the theatre, the museum and ranger talks
6. Holocaust Museum Permanent Exhibition (from March - August)
7. National Archives
Access to the Archives does not require a ticket, but the Timed Entry is recommended in the tourist season due to long lines. Guided tours are also available.
www.archives.gov/nae/visit/ and go to "Plan Your Visit"
8. Bureau of Engraving and Printing
The BEP requires tickets for admission from March through August but these are only available on a same-day basis
9. Mount Vernon
Advance tickets are not required, but you are now able to reserve a particular time for a mansion tour if you buy tickets ahead of your visit.
Must reserve 14-90 days in advance; no reservations outside these timeframes
11. State Department, Diplomatic Reception Rooms
12. Marine Corps Evening Parade
Advance reservations for the Friday evening parades at the Marine Corps Barracks are highly recommended. The Tuesday evening parades at the Iwo Jima Memorial do not require any reservations. Both of these parades take place only in the summer months.
Many of the "pay" museums offer ticketing in advance. Of those, only consider getting tickets in advance (during the tourist season) for the International Spy Museum because those tickets are time-specific; some times do get sold out; and because the lines to purchase tickets once you get here can be quite long.
TICKETS FOR FOREIGN VISITORS
Foreign visitors can obtain tickets online or in person to any of these attractions except for tours of the White House. The White House website directs foreign visitors to go through their Embassy to request tickets but no embassies now process these requests. Some foreign visitors have reported success in obtaining tickets by contacting a U.S. Representative (just as U.S. citizens do).