The restorers scoured the country, tapping into a network of collectors and aircraft aficionados to locate a vintage replacement. The cap, a stylish black affair with “B-29” and “Boeing” written to form the wings of a silhouetted bomber, was gone. But among the missing pieces was the cap that snapped into the control wheel where the pilot, Col. Workers invested an estimated 300,000 hours on the task, sorting through countless parts and polishing its aluminum skin until the iconic B-29 Superfortress - one of the most famous planes in the world - once more took shape. Over the years it had been disassembled, spread across multiple buildings, birds had nested in its engines, a turret had been smashed, its wheels had decayed, and its parts were corroded from being left out in the wind, sun and rain. In the 1980s, the Smithsonian began restoring the Enola Gay, the plane that dropped the atomic bomb on Hiroshima. Credit National Air and Space Museum, Smithsonian Institution