This museum chronicles the story of the mastery of flight, from Kitty Hawk to outer space. It holds the largest collection of historic aircraft and spacecraft in the world -- so many, in fact, that the museum is able to display only about 20% of its artifacts at any one time. To supplement its space, the National Air and Space Museum has just opened an extension gallery, the Steven F. Udvar-Hazy Center, at Washington-Dulles International Airport, to display many more. The center, which debuted in December 2003, will also serve as the Air and Space Museum's primary restoration facility. Shuttle buses run regularly between the two sites, but allow lots of time for the excursion, since the Udvar-Hazy Center is at least 45 minutes away. The 2003 timing was intentional, since 2003 marked the 100th anniversary of Orville and Wilbur Wright's 12-second flight in 1903. The National Air and Space Museum commemorated the event at this location by staging a special exhibit, "The Wright Brothers and The Invention of the Aerial Age," which continues into 2005.

At any rate, you should plan to spend a couple of hours here. During the tourist season and on holidays, arrive before 10am to make a beeline for the film ticket line when the doors open. The not-to-be-missed IMAX filmsshown here are immensely popular, and tickets to most shows sell out quickly. You can purchase tickets up to 2 weeks in advance, but they are available only at the Lockheed Martin IMAX Theater box office on the first floor. Two or more films play each day, most with aeronautical or space-exploration themes; To Fly and Space Station 3D are two that should continue into 2004. Tickets cost $7.50 for adults, $6 for ages 2 to 12 and 55 or older; they're free for children under 2. You can also see IMAX films most evenings after the museum's closing; call for details (tel. 202/357-1686).

You'll also need tickets to attend a show at the Albert Einstein Planetarium, which creates "an astronomical adventure" as projectors display blended space imagery upon a 70-foot diameter dome, making you feel as if you're traveling in 3-D dimension through the cosmos. The planetarium's main feature, called "Infinity Express, A 20-Minute Tour of the Universe," gives you the sensation that you are zooming through the solar system, as it explores such questions as "how big is the universe?" and "where does it end?" Tickets are $7.50 for adults, $6 for ages 2 to 12 and 55 or older; you can buy an IMAX film and planetarium combo ticket for $12 per adult, $10 per child.

How Things Fly, a gallery that opened in 1996 to celebrate the museum's 20th anniversary, includes wind and smoke tunnels, a boardable Cessna 150 airplane, and dozens of interactive exhibits that demonstrate principles of flight, aerodynamics, and propulsion. All the aircraft, by the way, are originals.

Kids love the walk-through Skylab orbital workshop on the first floor. Other galleries here highlight the solar system, U.S. manned space flights, sea-air operations, and aviation during both world wars. An important exhibit is Beyond the Limits: Flight Enters the Computer Age, illustrating the primary applications of computer technology to aerospace. Explore the Universe presents the major discoveries that have shaped the current scientific view of the universe; it illustrates how the universe is taking shape, and probes the mysteries that remain. In 2002, the museum added a set of six, two-seat Flight Simulators to its first floor galleries (the Udvar-Hazy Center has several more), allowing visitors to climb aboard and use a joystick to pilot an aircraft. For 3 minutes you truly feel as if you are in the cockpit and airborne, maneuvering your craft up, down, and upside-down on a wild adventure, thanks to virtual reality images and high-tech sounds. You must pay $6.50 to enjoy the ride and measure at least 48 inches to go it alone; children under 48 inches must measure at least 42 inches and be accompanied by an adult.

The museum's cafeteria, The Wright Place, offers food from three popular American chains: McDonald's, Boston Chicken, and Donato's Pizza. Best of all, the cafeteria serves up a great view of the Capitol.