its in the museum where all those ghouls (the people with no skin)
took refuge go there.its in downtown DC.
You mean the Museum of History and the Ghouls have made it Underworld but I think it is where some slavers are around the side of the building behind the Washington Monument (Don't know much American History :P ) and the slavers attack if you go past them so go around to a little entrance just next to the steps on the right and you can find a memorial place with it in there, but 1 slaver will attack you as they are the only friendly slaver unless you steal something and get caught!