Completed in 1881 as the first U.S. National Museum, this redbrick and sandstone structure was the scene of President Garfield's Inaugural Ball. (It looks quite similar to the Castle, so don't be confused; from the Mall, the Arts and Industries Building is the one on the left.) From 1976 through the mid-1990s, it housed exhibits from the 1876 U.S. International Exposition in Philadelphia -- a celebration of America's centennial that featured the latest advances in technology. Some of these Victorian tools, products, art, and other objects are on permanent display. The building displays rotating exhibits, such as one offered in 2003: "Changing the Face of Power: Women in the U.S. Senate," which displayed 35 black-and-white photographs of women senators.

Singers, dancers, puppeteers, and mimes perform in the Discovery Theater (open all year except Aug, with performances weekdays and on selected Sat). Call tel. 202/357-1500 for show times and ticket information; admission of about $5 is charged.

Don't miss the charming Victorian-motif shop on the first floor. Weather permitting, a 19th-century carousel operates across the street, on the Mall.