Never been there and wouldn't mind popping over to see it whilst in New York.
Roughly how long would it takes to seee the main things such as The White House, Lincoln and Jefferson Memorials, Pentagon (assuming you can get reasonably close to see it?) etc?
Roughly how long would it takes to seee the main things such as The White House, Lincoln and Jefferson Memorials, Pentagon (assuming you can get reasonably close to see it?) etc?