National Museum of Natural History

The Hope Diamond, a 45-carat deep-blue stone with a long and storied ownership history, draws crowds to the gem and mineral galleries of the Smithsonian's National Museum of Natural History. It is one of the most visited museums in the world, welcoming nearly seven million people a year to its domed Beaux-Arts building on the National Mall, which opened in 1910.

Visitors enter beneath the rotunda, where a mounted African bush elephant has stood since the late 1950s. Beyond it, the David H. Koch Hall of Fossils – Deep Time traces the history of life on Earth with skeletons including a Tyrannosaurus rex. The Sant Ocean Hall is anchored by a full-size model of a North Atlantic right whale, and the Hall of Human Origins examines human evolution through fossils and reconstructions.

The museum suits families and anyone curious about the natural world. Seeing the main halls takes at least half a day.