"I presume that you are referring to the building wherein meets the state legislature, because the city of Washington DC is, of course, your nation's capital, but does however contain the nation's capitol. I really get depressed by Americans who can't tell the difference, as well as by the ones who do Darwin Award-worthy feats but fail to die as a result (as per this article)."

Actually, it's the building where the FEDERAL legislature sits, each state and commonwealth in the union having its own capitol within its capital. Since the city of Washington and the District of Columbia are coterminous, one really couldn't say that one is "within" the other. (The idea for doing this was so that no state could claim precedence as the "home" of the nation's capital.)

So, yes - some of us Americans *CAN* tell the difference, thank you.