What it's Like To Work in the Biggest Building in the World (bbc.com)
To build a fleet of giant airliners requires a building just as big. Boeing's Everett Factory, built to construct the famous 747, is the biggest enclosed structure in the world. BBC Future: When you're building some of the world's biggest airliners, you need an equally outsized building. When Boeing decided to build the 747 -- a plane so big it would become known around the world as the jumbo jet -- they had to build a factory large enough to build several of them at the same time. If you've ever seen a 747 from close quarters you'll know just how giant Boeing's jumbo is. So it's no surprise the factory which ended up building has to be very big indeed. How big? Try the biggest enclosed building in the world.
Boeing started work on the Everett factory in 1967, just as the Boeing 747 project was starting to gather pace. Bill Allen, Boeing's charismatic chief, had realised the company would need a huge amount of space if they were going to build an airliner big enough to carry 400 passengers. They chose an area of woodland some 22 miles (35km) north of Seattle, near an airport that had served as a fighter base during World War Two. [...] Today, the Everett factory easily dwarfs any other building in the world by volume, with the Guinness Book of Records reporting that it occupies 72 million cubic feet (13.3 million cubic metres).
[...] Each shift has as many as 10,000 workers, and there are three shifts each day. Over the course of 24 hours, the factory has a population only a little less than the Australian city of Alice Springs. Reese has worked for Boeing for 38 years -- 11 of them running the factory tours -- but says he can still remember his first impression of the factory. "It was very awe-inspiring the first time -- and I would have to say every day since, too. It changes constantly. Each day there's something new." The Everett factory is so big that there's a fleet of some 1,300 bicycles on hand to help cut travel time. It has its own fire station and medical services on station, and an array of cafes and restaurants to feed the thousands of workers.
Boeing started work on the Everett factory in 1967, just as the Boeing 747 project was starting to gather pace. Bill Allen, Boeing's charismatic chief, had realised the company would need a huge amount of space if they were going to build an airliner big enough to carry 400 passengers. They chose an area of woodland some 22 miles (35km) north of Seattle, near an airport that had served as a fighter base during World War Two. [...] Today, the Everett factory easily dwarfs any other building in the world by volume, with the Guinness Book of Records reporting that it occupies 72 million cubic feet (13.3 million cubic metres).
[...] Each shift has as many as 10,000 workers, and there are three shifts each day. Over the course of 24 hours, the factory has a population only a little less than the Australian city of Alice Springs. Reese has worked for Boeing for 38 years -- 11 of them running the factory tours -- but says he can still remember his first impression of the factory. "It was very awe-inspiring the first time -- and I would have to say every day since, too. It changes constantly. Each day there's something new." The Everett factory is so big that there's a fleet of some 1,300 bicycles on hand to help cut travel time. It has its own fire station and medical services on station, and an array of cafes and restaurants to feed the thousands of workers.
By footprint, the flower auction in Aalsmeer is quite a bit larger (https://en.wikipedia.org/wiki/Aalsmeer_Flower_Auction)
I worked there for a while, many years ago. We got around on bicycles; customers on the far end of the building were half an hour from our office (which lay on one of the corners). There were very few signs around the building, so you had to know where you were going. Having said that, various areas had a different feel to them - in that sense it was like a city. Travelling by bike was fairly dangerous, as you shared the 'roads' with the electrical 'trains' that carry the flowers to and from.
Work starts at six in the morning, and finishes at around two in the afternoon. There is a visitor gallery, running above the floor where the actual work happens. It's worth a visit - but do come in the morning, as it is mostly deserted in the afternoon.
A video is worth 1000 words ...
Boeing Everett Factory - National Geographic