The 'pregnant plane' that can give birth to a new 787

Near the US city of Seattle, the world's biggest building - 100 acres under one roof - is used to piece together sections of plane from different parts of the world, such as Japan, the UK and Italy.

But to transport aircraft wings, nose cones and tailfins to the US, specially adapted 747s have been designed. They are just big enough to hold the aircraft parts - a hi-tech version of a ship in a bottle.

Dallas Campbell visited the facility in Everett, Washington, to see the Boeing 747 Dreamlifter in action.

UK viewers can see Dallas Campbell's full report in the second episode of Supersized Earth. The series begins on Wednesday 21 November at 20:00 GMT on BBC One. Or catch up later on the BBC iPlayer using the link above.