The Mini-Guppy is a Boeing 377 Stratocruiser airliner that was converted by Aero-Spacelines into a specialty cargo plane that was used to transport very large items. You can read more about it at: http://www.tillamookair.com/aerospacelines-mini-guppy. There are even larger versions called the Pregnant Guppy and Super Guppy. An image of the whole place can be seen at: https://pbase.com/dlgphoto/image/172711481.