The Boeing 747 'Dreamlifter' is the world's longest cargo aircraft and certainly one of the more visually striking as well. With just four built, it is also among the rarest freighters in the world today. Much like its counterpart over at Airbus – the Beluga (and later the BelugaXL) – Boeing designed this mammoth aircraft to transport components for its 787 Dreamliner from worldwide suppliers to its US factories.