Before you step inside the museum, stop outside first, on the Ninth Street side of the building, to visit the new butterfly garden. Four habitats -- wetland, meadow, wood's edge, and urban garden -- are on view, designed to beckon butterflies and visitors alike. The garden is at its best in warm weather, but it's open year-round.

Now go inside. Children refer to this Smithsonian showcase as "the dinosaur museum," since there's a dinosaur hall, or sometimes "the elephant museum," since a huge African bush elephant is the first amazing thing you see if you enter the museum from the Mall. Whatever you call it, the National Museum of Natural History is the largest of its kind in the world, and one of the most visited museums in Washington. It contains more than 124 million artifacts and specimens, everything from Ice Age mammoths to the legendary Hope Diamond. The same warning applies here as at the National Museum of American History: You're going to suffer artifact overload, so take a reasoned approach to sightseeing.

If you have children in your crew, you might want to make your first stop the first-floor Discovery Room, which is filled with creative hands-on exhibits "for children of all ages." Call ahead or inquire at the information desk about hours. Also popular among little kids is the second floor's O. Orkin Insect Zoo, where they enjoy looking at tarantulas, centipedes, and the like, and crawling through a model of an African termite mound. The Natural History museum, like its sister Smithsonian museums, is struggling to overhaul and modernize its exhibits, some of which are quite dated in appearance, if not in the facts presented. So a renovation of the gems and minerals hall has made the Janet Annenberg Hooker Hall of Geology, Gems, and Minerals worth a stop. You can learn all you want about earth science, from volcanology to the importance of mining in our daily lives. Interactive computers, animated graphics, and a multimedia presentation of the "big picture" story of the earth are some of the things that have moved the exhibit and the museum a bit further into the 21st century.

Scheduled to open on the first floor (the Rotunda floor) in November 2003 is the Kenneth E. Behring Hall of Mammals, where visitors can operate interactive dioramas that explain how mammals evolved and adapted to changes in habitat and climate over the course of millions of years. At least 274 models of mammals and a dozen fossils are on display. This exhibit represents the first time the mammal hall has been updated since 1963. Also, don't miss African Voices Hall, which presents the people, cultures, and lives of Africa, through photos, videos, and more than 400 objects.

Other Rotunda-level displays include the fossil collection, which traces evolution back billions of years and includes a 3.5-billion-year-old stromatolite (blue-green algae clump) fossil -- one of the earliest signs of life on Earth -- and a 70-million-year-old dinosaur egg. Life in the Ancient Seas features a 100-foot-long mural depicting primitive whales, a life-size walk-around diorama of a 230-million-year-old coral reef, and more than 2,000 fossils that chronicle the evolution of marine life. The Dinosaur Hall displays giant skeletons of creatures that dominated the earth for 140 million years before their extinction about 65 million years ago. Suspended from the ceiling over Dinosaur Hall are replicas of ancient birds, including a life-size model of the pterosaur, which had a 40-foot wingspan. Also residing above this hall is the jaw of an ancient shark, the Carcharodon megalodon, which lived in the oceans 5 million years ago. A monstrous 40-foot-long predator, with teeth 5 to 6 inches long, it could have consumed a Volkswagen Bug in one gulp. In an effort to update this exhibit, the museum in 2001 mounted a digital triceratops (that is, a computerized rendering of that dinosaur); you can manipulate the image to learn more about it.

Don't miss the Discovery Center, funded by the Discovery Channel, featuring the Johnson IMAX theater with a six-story-high screen for 2-D and 3-D movies (T-Rex: Back to the Cretaceous and Galapagos were among those shown in 2002), a six-story Atrium Cafe with a food court, and expanded museum shops. In spring 2002, the museum opened the small Fossil Café, located within the dinosaur exhibit on the first floor. In this 50-seat cafe, the tables' clear plastic tops are actually fossil cases that present fossilized plants and insects for your inspection as you munch away on smoked turkey sandwiches, goat cheese quiche, and the like.

The theater box office is on the first floor of the museum; purchase tickets as early as possible, or at least 30 minutes before the screening. The box office is open daily from 9:45am through the last show. Films are shown continuously throughout the day. Ticket prices are $7.50 for adults and $6 for children (2-12) and seniors 55 or older. On Friday nights from 6 to 10pm, the theater stages live (no cover) jazz nights, starring excellent local musicians