The history of Washington, D.C., is so intimately tied up with the history of the federal government that it’s easy to forget that the two are not always identical. Washington has many museums devoted to the government and the nation, but until now there was none about the city itself. Filling this gap is the City Museum of Washington, D.C. ( www.citymuseumdc.org ), operated by the Historical Society of Washington, D.C., in the old Carnegie Library at Mount Vernon Square. Exhibits include an interactive archeology laboratory and a multimedia show that, in the words of a museum spokesman, “uses surprising twists and turns, including fantasy and time travel, and nifty visual effects to bring Washington’s history to life.” A library with archives and manuscripts dating from the early 1700s is open to the public.