National Museum of Natural History

This is one of the great natural history museums in the world. The giant dinosaur fossils, glittering gems, creepy-crawly insects, and other natural delights -- 124 million specimens in all -- attract nearly 6 million visitors annually. Highlights include getting between Tyrannosaurus Rex and his dinner, a feisty Triceratops (the two giant fossils are poised for action, as are the other occupants of the popular Dinosaur Hall); watching out for the cheetah above you on the tree branch in Mammal Hall, which explains mammals' evolution, diversity, and role in the food chain; and drooling over the jewels like Marie Antoinette's earrings, the Rosser Reeves ruby, and the Hope Diamond, a blue gem found in India and reputed to carry a curse (Smithsonian guides are quick to dismiss this notion) in the Janet Annenberg Hooker Hall of Geology, Gems, and Minerals.

Ocean Hall, the museum's largest exhibit, scheduled to open in September 2008, will allow you to view the vivid ecosystem of a living coral reef. The "Ocean Explorer" theater simulates taking you into the depths of the sea.Watch colorful butterflies, hairy-legged tarantulas, and dozens of other live insects at the O. Orkin Insect Zoo, named for the pest-control magnate who donated money to modernize the exhibits. Tarantula feedings are Tuesday through Friday at 10:30, 11:30, and 1:30.

The IMAX theater shows 2- and 3-dimensional natural-history films, including the 3-D T-REX, throughout the day. It's open Friday evenings from 6 for the "IMAX and Jazz Café[ac]": live entertainment, food, and special IMAX films. Tickets can be purchased at the museum box office. Watch paleontologists at work in the glassed-in fossil labs throughout Dinosaur Hall. A list of current projects -- from cleaning and prepping new stegosaurus bones, to painting replicas of 15-million-year-old giant sharks' teeth -- is posted. Theme gift shops are set up in the museum's different sections. Pick up a dinosaur fossil kit in Dinosaur Hall, a stuffed walrus in Mammal Hall, or a great white shark tub toy in Ocean Hall. If you visit in spring, don't miss the quirky orchid and train show.