Additional Note: In HTTP/1.1, even though the web browser connects to the same IP address and port, to many web-servers, there is a slight difference between localhost and 127.0.0.1. Depending what is in the address bar, your browser will send a request header field with either Host: localhost or Host: 127.0.0.1 in it.
Washington DC Museum Free Days. Most Washington, DC museums are Free seven days a week. Crowds and parking are always an issue in the Capitol, so some planning and patience will make your visit more enjoyable. Also, see transportation and parking info below the list.
When in DC, be ready to walk. 7-10 days is plenty of time. I agree that you could spend ages in DC and still not see it all. There is simply SO much to do there and a lot of it is truly a bargain or free. Smithsonian Museums are great. I also recommend a visit to Arlington National Cemetery and the Iwo Jima Memorial. It is just a short metro ride.