— Up, up, up visitors walk, out of the darkness and into the light.
About sixty percent of the vast new National Museum of African American History and Culture, which opens Saturday, is underground.
Partly, that's to comply with height restrictions imposed on structures built on the National Mall, and partly, that's because a building so large — 400,000 square feet — would look ridiculous if it were entirely above grade, said the museum's lead architect, Philip Freelon.
But founding director Lonnie Bunch III and his curators have made a virtue of necessity. Objects in the murkiest parts of the museum, such as ballast bars found in the wreckage of a...