Exhibits on the first floor (enter on Constitution Avenue) explore the development of farm machinery, power machinery, transportation, timekeeping, phonographs, and typewriters. The Palm Court on this level includes the interior of Georgetown's Stohlman's Confectionery Shop as it appeared around 1900 and part of an actual 1902 Horn and Hardart Automat, where you can stop and have an ice cream. You can have your mail stamped "Smithsonian Station" at a post office that had been located in Headsville, West Virginia, from 1861 to 1971, when it was brought, lock, stock, and barrel, to the museum. An important first-floor exhibit, "A Material World," deals with the changing composition of artifacts--from predominantly natural materials such as wood and stone to the vast range of synthetics we have today. "Information Age" considers the ways information technology has changed society during the past 150 years. And "Science in American Life" analyzes the impact of science on society from the 1870s to the present.

If you enter from the Mall, you'll find yourself on the second floor. Until late 1998, you would have seen hanging in an alcove here, the huge, original Star-Spangled Banner, 30 by 42 feet, that inspired Francis Scott Key to write the U.S. national anthem in 1814. The flag is undergoing restoration work and will return to its niche by late 2001; in the meantime, you should be able to watch the conservators at work behind a glass wall on this floor.

The museum holds many other major exhibits. "After the Revolution" focuses on the everyday activities of ordinary 18th-century Americans. "Field to Factory" tells the story of African-American migration, south to north, between 1915 and 1940. The J Foucault Pendulum is a copy of the original model that was exhibited in Paris in 1851 with the accompanying teaser, "You are invited to witness the earth revolve." (The pendulum vibrates in a single plane, tracing in sand what seems to be a scattered series of lines, but what is actually the proof of the Earth's rotation.) Don't miss it!

One of the most popular exhibits on the second floor is "First Ladies: Political Role and Public Image," which displays the first ladies' gowns and tells you a bit about each of these women. Infinitely more interesting, I think, is the neighboring exhibit, "From Parlor to Politics: Women and Reform in America, 1890-1925," which chronicles the changing roles of women as they've moved from domestic to political and professional pursuits.

Head for the third floor if you want less of a crowd. Here are a vast collection of ship models, uniforms, weapons, and other military artifacts; major exhibits focus on the experiences of GIs in World War II (and the postwar world) as well as the wartime internment of Japanese Americans. Other areas include Money and Medals, Textiles, Printing and Graphic Arts, and Ceramics. Here, too, is the first American flag to be called Old Glory (1824).

Inquire at the information desk about highlight tours, films, lectures, and concerts, and hands-on activities for children and adults. The gift shop is vast--it's the largest of the Smithsonian shops.