The Smithsonian Institution's National Air and Space Museum (NASM) remains one of the world's most visited museums precisely because it embodies the "romance of technological progress." From its origins in the US National Museum of the early twentieth century to the opening of its first dedicated building in 1976 and beyond, visitors have flocked to the NASM to see exhibits on the wonders of aerospace technology. An attempt to depart from that narrative in the 1990s by telling the story of the atomic bombings of Japan was crushed by an organized campaign. In the aftermath, the museum reverted to its old pattern, albeit broadened to include greater diversity in the historical actors it featured. Today, as NASM rebuilds its original building, it is again striving, albeit more cautiously, to stretch the limits of its traditional mission.