The looming immensity of Moffett Field's Hangar One, built in 1933 to house the world's largest--and last--rigid-frame dirigible, is an unforgettable South Bay landmark. The lighter-than-air Macon cost 2.5 million Depression-era dollars and could hold 100 men and five Sparrowhawk biplanes, yet its silvery bulk hovered silently or sailed up to 80 miles an hour. It drew crowds as it darkened the skies around Mountain View until it broke up in a storm...