Arguably the most popular of the Smithsonian museums, so crowds are pretty much guaranteed. Wave to Henry, the elephant who guards the rotunda, then zip to the 2nd floor鈥檚 Hope Diamond, a 45.52-karat bauble that's said to have cursed its owners, which included Marie Antoinette.The giant squid (1st floor, Ocean Hall), live butterfly pavilion and tarantula feedings provide additional thrills at this kid-packed venue. The beloved dinosaur hall, centered on the Nation鈥檚 T-Rex, has reopened after being revamped.
Adults will find lots to love here too: Easter Island heads (lobby at the Constitution Ave entrance), mummies (2nd floor), ground-floor halls devoted to mammals and oceans, and a vibrant temporary exhibition program.
The butterfly pavilion has a separate admission fee (adult/child two to 12 years $7.50/6.50); it's free on Tuesdays.
On select days, usually in spring and summer, the museum extends its hours and stays open until 7:30pm.