Washington is a city of famous museums--the Smithsonian, the National Archives, even the White House. But could those attractions be too famous? Visitors who are drawn to them almost automatically may not realize that the nation's capital boasts a second tier of smaller, more specialized museums that are equally fascinating and often possess certain distinct advantages over their bigger, better-known brethren. For starters, they are less crowded and often inexpensive or free. In those institutions, adventurous tourists can find colorful, offbeat exhibits highlighting world-class collections, in some cases the only ones of their kind.
Consider the example of Mimi Donaldson, 57,...