Newseum in Washington D.C.
If you're in DC, check out the Newseum. They have some interesting exhibits going on: FBI and G-Men (from gangsters to terrorists) and Pulitzer Prize Photographs. This is a great place to take kids too (i.e. news-anchor simulation of green screen).
World Trade Center:
Berlin Wall (I heard that they had to alter the profanities on these walls for public display):