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.

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.

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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.

The site had only minor road access to the nearest highway and no railway connection, and in the forest wild bears roamed

An article in the Daily Herald, Everett’s local paper, recalls just how out of the way the airport was. According to Joe Sutter, the engineer who masterminded the 747 project, the site had only minor road access to the nearest highway and no railway connection. In the forest roamed wild bears.

At the same time Boeing was building the prototype of the world’s biggest airliner, it was also having to construct the factory to make them in.

Today, the Everett factory easily dwarfs any other building in the world by volume, with the Guinness Book of Records reporting that it occupies 472 million cubic feet (13.3 million cubic metres).

“We’ve overlaid the building over some of the most famous landmarks around the world,” says David Reese, who helps runs the factory tours at Everett. “We have various famous places like Versailles, the Vatican and Disneyland, and you see them when you start the factory tour.

Everett’s main building covers 97.8 acres (39 hectares), more than 30 times as big as London’s Trafalgar Square

“I remember I did an interview with the BBC a few years ago, and I thought ‘I wonder what the volume of Wembley Stadium is?’ Well, it turns out you can fit 13 of them in the volume of our factory.”

The Everett plant still produces a dwindling number of 747 freighters, but today it mostly concentrates on the smaller 767, 777 and 787 models. To build that fleet of planes requires lots of room. Everett’s main building covers 97.8 acres (39 hectares), more than 30 times as big as London’s Trafalgar Square.

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.  Overhead are a multitude of cranes used to move some of the heavier aircraft parts as the planes start to take shape. The operators, Reese says, are some of the most highly skilled and best-paid workers at the factory.

In summer, if it gets too hot, Reese says, they just open the massive doors to let in the breeze

There are a few rules for working in, or even just visiting, the factory. “We do require proper footwear, so no open-toed shoes and no high heels for the ladies – anything that could possibly cause a fall or damage your feet – and you have to wear safety glasses at all times in the factory. Constantly. That can be an issue with some of our visitors, they say things like ‘Oh, I wear reading glasses, that will be enough.’ It’s not.”

The factory boasts some surprising features. While there is ventilation, there is no air conditioning. In summer, if it gets too hot, Reese says, they just open the massive doors to let in the breeze. In winter, the effect of the more than one million lights, the huge amount of electric equipment and some 10,000 human bodies also helps moderate the temperatures. “I only have to wear a sweater or a light jacket and that’s sufficient.”

There is a longstanding urban myth that the building is so large and high that clouds form at the top of it. Not quite so, says Reese. “The building was still being constructed as the first plane was being built, and one wall was not yet enclosed. We think that fog or mist from the outside and accumulated in the building, and it looked like a kind of hazy atmosphere.

“It’s the same thing when we had wildfires nearby, it got pretty hazy inside the factory.”

Reese says the factory’s days have an ebb and flow, the factory changing tasks as the day progresses.  “The second shift, that’s when there’s more crane activity when there isn’t quite as many people.

“When we move a finished aircraft out of the factory it’s driven over a freeway to an airport nearby, and in order not to startle the drivers too much, we tend to do that at night.”

Not just the world’s biggest building, but full of surprises too.

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