Howard Hughes' famous
Spruce Goose H-4 Hercules took it's one and only flight and became the largest airplane ever to fly. After its completion, it was three times larger than the largest aircraft built before it. Now surpassed by the Antonov 225, it still holds the records for widest wingspan and the largest flying boat ever.
It now resides at the Evergreen Aviation Educational Center in McMinnville, Oregon.