The Vehicle Assembly Building at Launch Complex 39, Kennedy Space Center, Florida.

All the Saturn V rockets for the crewed Apollo missions were assembled inside it (with the exception of the first, Apollo VII, which used a Saturn 1B rocket), and it is where Space Shuttles were mated to their external fuel tank and rocket boosters.

It is the eighth largest building in the world by internal volume, and the tallest single-storey building in the world. The flag on the side, added in 1976 for the US bi-centenary, is over 200 feet from top to bottom. The individual stars are each six feet across (1.83m), the stripes are nine feet wide (2.74m), wide enough that if laid flat an HGV or bus could drive along them, and the blue field is the size of a regulation basketball court.

It takes 45 minutes to open or close the bay doors at the ends of the building, which are 456 feet tall (139m), making them the largest doors in the world. For context, the pitch at Murrayfield, the home of Scottish rugby, is 100 metres from try-line to try-line, with in-goal areas usually 20m deep, so the whole pitch is 140m long from one dead-ball line to the other, almost exactly as long as these doors are high.

Assembled vehicles are moved from the VAB to the launch pads, either 39A or 39B, on a crawler vehicle. The VAB is 3.5 miles from the pads, the reason being that the blast-radius of a fully loaded Saturn V rocket was three miles.